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Your question is – If the sum of 5 consecutive numbers is equal to 15 and the average of first three numbers is twice less than the average of the last three numbers, find the value of the third number in the series. It is given that the average of the last three numbers is 4.

Your Correct answer: d

I have solved this problem thus, you can read my Explanation for your better understanding:

According to the question,
The sum of five consecutive numbers = 15 …..i
And the average of last three numbers = 4 …..ii
The average of first three numbers = average of last three numbers – 2
Hence, the average of first three numbers = 4 – 2 = 2 …..iii
Hence, the sum of first three numbers = 2(3) = 6 …..iv
And, the sum of last three numbers = 4(3) = 12 …..v
Thus, the value of the third number in the series = (i) – (iv) – (v) = 15 – 6 – 12 = -3
Hence, the correct answer is option d.

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