What is Q={x∈N: x<40 and the last digit of x is 7}?
Answer and explanation
Correct answer: Q={7,17,27,37}
List the natural numbers whose units digit is 7: 7, 17, 27, 37, 47, and so on. Applying the strict condition x<40 keeps 7, 17, 27 and 37, but removes 47 and every larger value. Therefore the correct roster form is Q={7,17,27,37}, which is option A. Option B contains 47, C contains 40 even though its last digit is 0, and D omits 37.
Frequently asked questions
What is the correct answer to this question?
Q={7,17,27,37}
Why is this the correct answer?
List the natural numbers whose units digit is 7: 7, 17, 27, 37, 47, and so on. Applying the strict condition x<40 keeps 7, 17, 27 and 37, but removes 47 and every larger value. Therefore the correct roster form is Q={7,17,27,37}, which is option A. Option B contains 47, C contains 40 even though its last digit is 0, and D omits 37.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: Decimal representation.
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