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.

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.

Which one is correct answer below?

a. -11
b. -12
c. -13
d. -3
e. None of the above

Default Asked on December 5, 2017 in GMAT.
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1 Answer(s)

    Thank you very much for your question. I’m very glad to know that you have come to a question-answer website to solve your problem. That means, you have a strong will to learn this math.  I really appreciate it. Thank you again.

    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.

    If you have more question, ask me.

    Brong Answered on December 5, 2017.
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