Gwen has recently purchased a cottage. She has arranged

to have well dug on the property. One in five wells that

were dug recently in the vicinity were dry, and 30% of the

others were contaminated. Find the probability of each of

the following:

a) Gwen's well will not be dry.

(b) Gwen's well will be uncontaminated, given that it is not dry.

(c) Gwen will have safe drinking water

from her well.

(d) Gwen will not have safe-drinking

water from her well.

Question

Jazlene Garrett

Mathematics

1 May, 20:41

Gwen has recently purchased a cottage. She has arranged

to have well dug on the property. One in five wells that

were dug recently in the vicinity were dry, and 30% of the

others were contaminated. Find the probability of each of

the following:

a) Gwen's well will not be dry.

(b) Gwen's well will be uncontaminated, given that it is not dry.

(c) Gwen will have safe drinking water

from her well.

(d) Gwen will not have safe-drinking

water from her well.

+2

Answers (1)

Know the Answer?

Sterling Marshall · 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