Question (57/66)

If mean of a, b, c is M and ab + bc + ca = 0, then the mean of a², b² and c² is ?

A = M²
B = 3M²
C = 6M²
D = 9M²

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(A)  A

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(B)  B

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(C)  C

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(D)  D

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Question (58/66)

If the average of 5 observations X, (X + 2), (X + 4), (X + 6) and (X + 8) is 11, then what is mean of the last 3 observations ?

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(A)  11

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(B)  13

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(C)  15

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(D)  17

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