M (Mean) = 20,500;
SD (Standard Deviation) = 55
1 ) 20,555 = 20,500 + 55 = M + 1 SD
Answer: 50% + 34.1% = 84.1%
2 ) 20.610 = 20,000 + 110 = M + 2 SD
Answer: 10% - ( 50% + 34.1% + 13.6% ) = 100% - 97.7% = 2.3%
3 ) 20,445 = 20,500 - 55 = M - 1 SD
Answer: 50% - 34.1% = 15.9%
Use trigonometry here.
sinx = opposite side/ Hypotenuse
so, sinx = 4/5 = 0.8
x= sin^-1(0.8) which is 53.13
Hope it helps
