A certain county has a population of 34,237 people. The county hospital is interested in estimating the number of people in the county with blood-type A−. To do this, they test blood samples from 245 patients. Out of this group, 12 have blood-type A−. Use this sample to estimate the number of people in the county with blood-type A−.

About 1677 people in the county will have blood-type A−.

Step-by-step explanation:

From the question, 12 out of 245 patients have blood-type A−.

To estimate the number of people in the county which has a population of 34,237 people with blood-type A−, we will assume that for every 245 people out of the 34,237 people, 12 of them have blood-type A−.

Let the number of people with blood-type A− in the county be x.

Now,

If 12 people out of 245 people have blood-type A−

Then, x people out of 34237 people will have blood-type A−

245 × x = 34237 × 12

245x = 410844

x = 410844/245

x = 1676.9

x ≅ 1677

Hence, about 1677 people in the county will have blood-type A−.