Question

Gwen has recently purchased a cottage. She has arranged

Answer 1

A) 0.8
B) 0.24
C) 0.56
D) 0.44

For A, since 1 in 5 is dry, 4 in 5 are not; 4/5 = 0.8

For B, we know that 30%, 0.3, of the ones that are not dry are contaminated:
0.3(0.8) = 0.24

For C, 100%-30%=70% of wells that are not dry are not contaminated; 0.7(0.8) = 0.56

For D, she will either have contaminated water or no water:
0.24+0.2 = 0.44