Answer:
The probability is 4.34%.
Explanation:
Given that in a group of 23 pupils, 4 play the flute only, 3 play the piano only and 15 play neither instrument, if a student is selected at random, to determine what is the probability the student plays both instruments the following calculation has to be done:
23 - 15 - 4 - 3 = 1
Therefore, only 1 student plays both instruments, with which the probability that if a student is chosen at random he will play both instruments is 1/23, that is:
23 = 100
1 = X
100/23 = X
4.34 = X
Therefore, the probability is 4.34%.