Answer:
3/16
Step-by-step explanation:
16 pupils, 11 play both, 1 plays piano only and 1 flute only
⇒ 11 + 1 + 1 = 13 pupils who play at least one instrument
⇒ 16 - 13 = 3 pupils who don't play either instrument
⇒ Out of the 16 total pupils, 3 play neither, putting this into numbers:
which is then also the answer.