Suppose 80% of people can swim. Suppose 70% of people can
whistle. Suppose 55% of people can do both. What percentage of people
can swim or whistle?

95%

Step-by-step explanation:

Let the proportion who can swim be denoted by P(S) while the proportion that can whistle be denoted by P(W)

The proportion that can swim and whistle will be P(S and W)

The proportion that can swim or whistle will be P(S or W)

To get the proportion that can swim or whistle will be P(S or W), we use

P(S or W)=P(S)+P(W)-P(S and W)

Given that P(W) is 70%, P(S) is 80% and P(S andW) is 55% then

P(S or W)=80%+70%-55%=95%

- 70

this is the answer for you hope it

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4