In a clothing store, 55% of the customers buy a shirt, 25% of the customers buy a pair of pants, and 20% of the customers buy both a shirt and a pair of
pants.
If a customer is chosen at random, what is the probability that he or she buys
a shirt or a pair of pants?
A. 0.225
B. 0.60
C. 0.30
D. 0.80

s= the customer buy a shirt

p= the customer buy pants

And we want to find this probability:

And we can use the definition of total probability and we have:

And replacing we got:

And the best answer for this case is:

B. 0.60

Step-by-step explanation:

For this case we can define the following events:

s= the customer buy a shirt

p= the customer buy pants

And we have the following probabilities given:

And we want to find this probability:

And we can use the definition of total probability and we have:

And replacing we got:

And the best answer for this case is:

B. 0.60

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: