Hi

really recommend us TI Calculator. 

However, z values are easy enough manually, and then going to Excel NORMSDIST(z)  

a. less than 95: P(z < (95-100)/10/sqrt(25) = P(z < -5/2) =NORMSDIST(-2.5)= .0062 

b. between 95 and 97.5: P(z< -1.25 - P(z< -2.5)= .1057 -.0062

TI ,makes this so easy) normalcdf(-2.5, -1.25)

c. above 102.2 = 1 -P(z < 1.1)= 1- .8643



d. there is a 65% chance that Xbar is above what value X? 

invNorm(.45) Or Excel NORMSINV(.45)= -.1257 = z

-.1257 = (X-100)/10/sqrt(25)

2(-.1257) + 100 = X  

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