Stocks and flows

Correct answer: B. It is measured at a point of time

Explanation: The defining feature of a stock is that it is measured at a particular point of time or on a specified date. Examples include wealth, capital, population, inventory, and government debt on a given date. A quantity written per year or measured during a period is generally a flow. A stock need not be zero and is not limited to expenditure.

Correct answer: C. It is measured over a period of time

Explanation: A flow is an economic quantity measured during a specified period, such as a month, quarter or year. National income, consumption expenditure, saving, exports and production are flows because they record an activity occurring over time. A stock, in contrast, is measured at one particular date, such as wealth or capital on 31 March. Therefore, option C correctly defines a flow.

Correct answer: D. Wealth and income

Explanation: Wealth is a stock because it represents the accumulated value of assets measured at a particular point in time. Income is a flow because it is earned during a period such as a month or year. Thus, option D gives the correct order: stock followed by flow. Option A contains the same two concepts in reverse order, while output and sales are normally flows and capital and bank deposits are stocks.

Correct answer: A. Stock variable

Explanation: Capital stock is the amount of capital existing at a particular point in time, such as the end of a financial year. A quantity measured on a date or at the end of a period is a stock variable. Investment expenditure, however, records additions to capital during a period and is therefore a flow. Hence, option A is correct and option D describes a different flow concept.

Correct answer: B. Flow variable

Explanation: An addition to capital during a year is investment or capital formation recorded over the duration of that year. Because it measures an economic activity across a time interval, it is a flow variable. The capital stock itself would be measured at a particular date and would be a stock. Therefore, option B is correct; options A, C and D refer to point-in-time or accumulated quantities.

Correct answer: C. Saving in one year

Explanation: The phrase “in one year” identifies a definite time interval. Saving measured over that interval is a flow variable because it records the amount saved during the year. A bank balance today, wealth at year-end, and population on a specified date are measured at particular points in time and are stocks. Thus, option C is the only example with a clear period-based measurement.

Correct answer: D. Cash held today

Explanation: Cash held today is measured at a specific point of time, so it is a stock variable. The word “today” identifies the date or time point at which the amount exists. Monthly income, annual consumption expenditure and one-day output are measured over intervals and are flows. Therefore, option D correctly identifies the point-of-time example and distinguishes it from period-based measures.

Correct answer: A. Flow variable

Explanation: Saving is the part of income that remains after consumption during a specified period. It can be expressed as saving equals income minus consumption, with both measured over a month, quarter or year. Since saving records an amount generated during an interval, it is a flow variable. The accumulated stock of savings held on a particular date would instead be a stock variable.

Correct answer: B. Stock variable

Explanation: Total accumulated household savings on a specified date represent the amount held at one point in time. Such a balance is a stock variable, because it is measured on a date rather than over a period. Daily income and annual expenditure are flows since they are measured during time intervals. Thus, option B is correct, even though the saving accumulated through earlier periods came from flow variables.

Correct answer: C. Flow variable

Explanation: Rent income per month is measured over the interval of one month. It records the income earned during that period, so it is a flow variable. The amount of property owned or debt outstanding on a particular date would be a stock. Therefore, option C is correct. The expression “per month” is a strong clue that the quantity refers to a duration rather than a single point in time.

Correct answer: D. Stock variable

Explanation: The value of a house on a particular date is measured at one point in time. It represents the value of an asset held at that date, so it is a stock variable. Income and rent are generally flows because they are received over a month or year. Option D is therefore correct; the phrase “on a date” is the key clue indicating a point-of-time measurement.

Correct answer: A. Income and output

Explanation: Income and output are both measured over a specified period, such as a month, quarter or year. Income records earnings during the period, while output records production during the period; therefore both are flow variables. Wealth, capital, bank balances, cash holdings and debt are normally measured at a point in time and are stocks. Hence, option A is the only all-flow pair.

Correct answer: B. Capital and wealth

Explanation: Capital and wealth are stocks because they describe accumulated quantities or asset values existing at a particular point in time. Income, expenditure, investment, saving, output and sales are flows when measured over a period such as a year. Thus, option B contains only stock variables. The time dimension is essential: the same word may require context, but these textbook classifications are standard here.

Correct answer: C. Bank deposit and interest income

Explanation: A bank deposit is a stock because its balance is measured at a particular point in time. Interest income is a flow because it is earned over a period, such as a month or year. Option C therefore gives stock first and flow second. Option A gives flow followed by stock, while B and D also reverse the requested order or contain a different classification pattern.

Correct answer: D. Income and wealth

Explanation: Income is a flow because it is earned and measured during a period such as a month or year. Wealth is a stock because it represents the accumulated value of assets held at a particular point in time. Therefore, option D correctly gives flow first and stock second. Option B reverses the order because capital is generally a stock and investment is a flow.

Correct answer: A. Flow variable

Explanation: Exports made during a year measure the value of goods and services sold to other countries over the duration of that year. Since the measurement covers a time interval, exports are a flow variable. Capital stock and national wealth are accumulated quantities normally measured at a particular date. Therefore, option A is correct, and the words “during a year” provide the decisive clue.

Correct answer: B. Stock variable

Explanation: The quantity of goods stored at a port on a particular day is measured at one specific point in time. It shows the inventory existing on that day, so it is a stock variable. A flow would measure goods entering, leaving or being produced during a period such as a month. Hence, option B is correct; the words “on a particular day” identify a point-in-time stock.

Correct answer: C. Flow variable

Explanation: Imports during a year measure the value of goods and services purchased from foreign countries over a specified period. Because the measurement is made across the year rather than on one date, imports are a flow variable. Total wealth and money supply are stocks when measured at a particular date. Therefore, option C is correct, and “during a year” is the relevant period indicator.

Correct answer: B. Stock variable

Explanation: Foreign exchange reserves on a specified date represent the total foreign currency and foreign assets held by a country at that point in time. They are therefore a stock variable. Changes in reserves during a month or year would be a flow, but the level existing on a date is a stock. Thus, option B is correct, with “on a date” providing the essential clue.

Correct answer: A. Today or on a date

Explanation: Words such as “today,” “on a date,” “at the end of the year” and “at a point in time” indicate that a quantity is measured at one specific moment. Such a quantity is a stock variable. By contrast, “per year,” “per month” and “during a period” refer to intervals and usually identify flows. Therefore, option A is the useful stock clue.

Correct answer: B. Per month

Explanation: “Per month” indicates that a quantity is measured over the interval of one month, not at a single instant. Income, expenditure, output and saving stated per month are therefore flow variables. A quantity available on a date or a total accumulated amount is generally a stock. Hence, option B is the useful clue for identifying a flow, while the other options suggest point-in-time stocks.

Correct answer: C. Flow variable

Explanation: The phrase “during the year” defines a time interval over which production is measured. Output produced throughout that interval is therefore a flow variable. A stock would describe the amount of capital, inventory or cash existing at one particular date. Thus, option C is correct. The distinction depends on the measurement period, not merely on the physical nature of the output.

Correct answer: D. Stock variable

Explanation: Goods available at the end of the year represent inventory existing at a particular point in time. Since the quantity is measured at the year-end date, it is a stock variable. Annual sales and monthly output are flows because they record activity over periods. Therefore, option D is correct. The phrase “at the end of the year” identifies a time point, even though that point follows a whole year of activity.

Correct answer: A. Flow variable

Explanation: GDP for one year measures the market value of final goods and services produced within the country during that year. Because production is recorded over a specified period, annual GDP is a flow variable. It is not a stock of wealth or capital existing on one date. Therefore, option A is correct. GDP can be compared across years precisely because it is measured for recurring time intervals.

Correct answer: B. Stock variable

Explanation: The total number or value of machines in a country on a specified date is measured at one point in time. It represents the existing capital stock, so it is a stock variable. Government expenditure would be a flow when measured over a financial year, and an intermediate good is a classification of a product rather than a time-based variable. Hence, option B is correct.