Question

A geneticist studying fruit flies finds that out of a total population of 400 he observes only 12 flies with red eyes, the rest have black eyes. The percentage of flies with red eyes is

Answer 1

The question says that in a population of 400 flies, only 12 had red eyes.

The total number of fruit flies in this case is 400.

and

The total number of flies having red eyes is 12.

To find out the percentage of fruit flies having red eyes, following formula is used:

$\frac{\textup{total number of flies having red eyes}}{\textup{total number of flies}}\times 100$

So, the percentage of red eye individual is;

$\frac{12}{400}\times 100 \\ \\=3$

Hence, the total percentage of red eye offspring is 3%.

Answer 2

Given: Total population of flies is 400, number of flies with red eyes is 12.

To find: The percentage of flies with red eyes.

Method: We know the total number of red eyed flies and the size of population. The percentage can be found by diving the number of red flies by the size of the population of the flies.

Solution:

Percentage of red eyed flies = $\frac{12 \times 100}{400} = \frac{3\times100}{100} = 3$

Hence the answer is 3% of the flies are red eyed.