Sarah is in a room with 6 other children. If the other child

[manoj.bableshwar]

Sarah is in a room with 6 other children. If the other children are 2, 4, 5, 8, 10, and 13 years old, is Sarah 7 years old?

(1) The age of the fourth oldest child is equal to the average (arithmetic mean) of the seven children’s ages.

(2) Sarah is not the oldest child in the room.

Can an expert please explain vvhy C

[tim]

Before we help with this question, we need you to show some effort of your own. What did you try on this question? Where did you get stuck?

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[krishnan.anju1987]

Is the answer C?

This is how I tried the question.
These are the possible values of x

x,2,4,5,8,10,13
2,x,4,5,8,10,13
2,4,x,5,8,10,13
2,4,5,x,8,10,13
2,4,5,8,x,10,13
2,4,5,8,10,x,13
2,4,5,8,10,13,x

The average of these seven numbers would be (42+x)/7.
1) says that the fourth number would be equal to average
Hence, (42+x)/7=5. Thus, x=-7. Not possible.

2)(42+x)/7=x. x=7

3) (42+x)/7=8 x=14

hence Insufficient

2) states says that x can't be the largest number. INSUFFICIENT

Together, x must be 7.

[RonPurewal]

perfect.