Question : The average of a set of 15 consecutive even numbers is 64. What is the difference between the largest and the smallest numbers belonging to this set?
Option 1: 26
Option 2: 27
Option 3: 25
Option 4: 28
Correct Answer: 28
Solution :
Use :
a
n
= a + (n - 1)d, where
a
n
= n
th
term of largest term of A.P
a = first term, n = number of terms, d = common difference
According to the question
n = 15 and d = 2
⇒ Difference between first term and the last term = a + (n – 1)d – a = (15 – 1)2 = 14 × 2 = 28
Hence, the correct answer is 28
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