12. Beth's scores on the six Earth science tests she took this semester are: 65, 72, 84, 85, 68, 100, 95, 55, 85, 75, 100
For this population, how many scores are within one standard deviation of the mean?
A)7
B) 5
C)6
D)4

explanation:

step-by-step explanation:

answer: cos [   arcsin (3/5) - arccos (1/2) ] =

step-by-step explanation: × = 3/5 = 0.6--> x = 36.87 and x = 180 - 36.87 = 143.13 deg

cos y = 1/2 --> y = +- 60 deg a. cos (x - y) = cos (143.13 - 60) = cos 83,13  

=

0.12

b. cos (36.87 - 60) = cos (-23.23) = 0.92

this is a good question! i'll do some research and come back when i have the answer!