Problem Solving

guerrero wrote:If after a number was added to a set consisting of all one-digit prime integers, the median of the set grew by 25%, which of the following cannot be the value of the number added?

4.8
5.0
√29
7.7
94/4

OA A

I'm not crazy about the ambiguous wording here.
Presumably the original set is {2, 3, 5, 7}
So, the median of this set is (3+5)/2 = 4

Answer choice B: Notice that if we add 5, we get {2, 3, 5, 5, 7}
So, the median is now 5.
This represents a 25% increase in the value of the median.

Answer choice C: Notice that if we add √29 , we get {2, 3, 5, √29, 7}
So, the median is now 5.
This represents a 25% increase in the value of the median.

Answer choice D: Notice that if we add 7.7 , we get {2, 3, 5, 7, 7.7}
So, the median is now 5.
This represents a 25% increase in the value of the median.

Answer choice E: Notice that if we add 94/4 , we get {2, 3, 5, 7, 94/4}
So, the median is now 5.
This represents a 25% increase in the value of the median.

Answer = A

Cheers,
Brent