Question

1. A team of biologists captured and tagged 70 deer in a forest. Two weeks later, the biologists captured a sample of 30 deer from the same forest, and found that 7 of them were tagged. How many deer would they estimate are in the forest?2. At first street elementary school, About 34% of the 785 students ride bicycles to school. About how many students ride bicycles to school?

Answer 1

Problem 1.

The initial sample of deer was 70, and all were tagged. The second event captured 30 and found 7 out of them tagged. Therefore, if we consider that 7 out of 30 was the ratio that represents the proportion of tagged to total, then we can write the following proportion to estimate the number(X) of deer in the population:

7 / 30 = 70 / X

where X can be solve by cross multiplying:

X = 70 * 30 / 7 = 300 deer.

Problem 2.

34% of 785 students ride theit bicycles to school, That is (recalling that 34% is written as 0.34 in decimal form):

0.34 * 785 = 266.9 so about 267 students ride their bicycles to school