A total of 9,180 people participated in a research study on the genetics of eye color. Of the participants, 4/9 had two

[BTGmoderatorLU]

Source: Manhattan Prep

A total of 9,180 people participated in a research study on the genetics of eye color. Of the participants, 4/9 had two parents with blue eyes, and of the remaining participants, 8/17 had one parent with blue eyes. How many participants, in total, had at least one blue-eyed parent?

A. 780
B. 2,700
C. 4,320
D. 6,480
E. 8,400

The OA is D

[deloitte247]

Total participant = 9180
Of the total participants, 4/9 had two parent2 with blue eyes
$$\frac{4}{9}\cdot9180=4080$$
remaining participants = 9180 - 4080 = 5100
Of the remaining participants, 8/17 had one parent with blue eyes
$$\frac{8}{17}\cdot5100=2400$$
Participant with two blue-eyed parent and one blue-eyed parent had at least one blue-eyed parent; so their total = 4080 + 2400
= 6480
Answer = option D

[Scott@TargetTestPrep]

Source: Manhattan Prep

A total of 9,180 people participated in a research study on the genetics of eye color. Of the participants, 4/9 had two parents with blue eyes, and of the remaining participants, 8/17 had one parent with blue eyes. How many participants, in total, had at least one blue-eyed parent?

A. 780
B. 2,700
C. 4,320
D. 6,480
E. 8,400

The OA is D

Solution:

The fraction of participants who had at least one blue-eye parent is:

4/9 + (1 - 4/9) x 8/17 = 4/9 + 5/9 x 8/17 = 68/153 + 40/153 = 108/153

Since there are a total of 9,180 participants, 9,180 x 108/153 = 60 x 108 = 6,480 participants had at least one blue-eye parent.

Answer: D