एक समान्तर श्रेणी में प्रथम पद (25) और सार्व अंतर (-2) है। पहले (20) पदों का औसत क्या होगा?
In an arithmetic progression the first term is (25) and the common difference is (-2). What is the average of the first (20) terms?
Explanation opens after your attempt
B. (6)
Concept
The last term is (25+19(-2)=-13), so the average is \(\frac{25-13}{2}=6\). Exam tip: the average is the average of first and last terms.
Why this answer is correct
The correct answer is B. (6). The last term is (25+19(-2)=-13), so the average is \(\frac{25-13}{2}=6\). Exam tip: the average is the average of first and last terms.
Exam Tip
अंतिम पद (25+19(-2)=-13) है इसलिए औसत \(\frac{25-13}{2}=6\) है। परीक्षा में औसत प्रथम और अंतिम पद का औसत होता है।
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