mpjena wrote:

question :

Two different groups of test-takers received scores on the GXYZ standardized test. Group A's scores had a norrmal distribution with a mean of 460 and standard deviatiation of 20. Group B's scores had a norrmal distribution with a mean of 520 and standard deviatiation of 40. If each group has the same number of test takers, what fraction of the test-takers whos scored below 440 belonged to group B.

a. 1/9

b. 1/8

c. 1/6

d. 4/17

e. 4/21

in first case, the area below 1 SD from the mean = (100% - 68%)/2= 16%

in second case, the area below 2 Sd is = (100% - 95%)/2= 2.5%

so the fraction = 2.5%/(16%+2.5%) = 2.5/18.5 = close to 1/8. since 1/9 and 1/8 are close to each other, could be 1/9.