The common fruit fly Drosophila melanogaster is the most studied organism in gen
ID: 2947186 • Letter: T
Question
The common fruit fly Drosophila melanogaster is the most studied organism in genetic research because it is small, easy to grow, and reproduces rapidly. The length of the thorax (where the wings and legs attach) in a population of male fruit flies is approximately Normal with mean 0.800 millimetres (mm) and standard deviation 0.078 mm. (a) What percentage of flies have thorax length less than 0.6 mm? (b) What percentage of flies have thorax length greater than 0.9 mm? (c) What percentage of flies have thorax length between 0.6 mm and 0.9 mm?
Explanation / Answer
Solution: mean = 0.800, sd = 0.078
(a) P(X < 0.6) = P(Z < (0.6-0.8)/0.078)
= P(Z < -2.5641)
= 0.0052
(b) P(X > 0.9) = P(Z > (0.9-0.8)/0.078)
= P(Z > 1.2821)
= 0.1003
(c) P(0.6 < X < 0.9) = P(-2.5641 < Z < 1.2821)
= 0.8945
Z = (x - mu)/s