how do i anwser this question

Question

In a survey into painkillers for a toothache, 3/5 of patients preferred ibuprofen, 1/5 said that paracetamol worked best and 17% found that aspirin was most effective. The rest of the 100 people surveyed had never had a toothache.

A patient is chosen at random.

 

a.  What is the probability of a patient not having had a toothache?

 

b.  In a village of 870 people, how many are likely to have never had a toothache?

Answer 1

If 3/5 of 100 people like ibuprofen then 60 people use it.

 

If 1/5 of 100 people like paracetamol then 20 people use it.

 

If 17% of 100 people like aspirin, then 17 people use it.

 

97 people are accounted for, so 3 did not get a toothache.

 

a.  Prob of no toothache = 3/100

 

b.  870 x 3/100 = 26.1 or 26 people