rajatr wrote:

One number, n, is selected at random from a set of 10 integers. What is the probability that ½ n + 13 = 0 ?

1 .The largest integer in the set is 13.

2. The arithmetic mean of the set is zero.

For n/2+13 = 0, n = -26.

From F.S 1, we have the largest integer as 13. Thus the set could have all 10 positive integers including 13 in which case the probability - 0. Also, the number -26 could be included in some other combinations of 10 integers, where the probability would be a non-zero entity. Insufficient.

From F.S 2, as the arithmetic mean of the set is zero, hence the sum of all the ten integers is zero. Again, the presence/absence of -26 is not ascertained from this fact statement.Insufficient.

Combining both, for set -26,-5,-3,-2,0,2,4,8,9,13 --> the probability is 1/10

Again, for the set -13,-4,-3,-2,-1,1,2,3,4,13 --> the probability is 0. Insufficient.

E.

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