Question 1105972: Suppose the weights of 11000 male students are normally distributed with mean 160 ponds and Variance of 40 ponds. Find the number of students with weights.
i- Less than 100 pounds
ii- Between 150 and 175 pounds
iii- Greater than 155 pounds
iv- Between 170 and 175 pounds
v- Greater than 210 pounds
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! SD is sqrt (40) or 6.32 pounds (the variance should be 40 pounds^2, since it is a quadratic term.)
les than 100 is essentially 0 since it is 60/6.32 sd s from the mean.
Between 150 and 175, z=(x-mean)/sd or (150-160)/6.32=-1.58 and (175-160)/6.32=+2.37. Probability of z between those is 0.9341
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greater than 155 is z > (155-160)/6.32>=-0.7911, probability is 0.7856
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between 170 and 175 is z between (170-160/6.32=1.58 and 15/6.32=2.37, probability is 0.0482.
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greater than 210 is a z > 50/6.32 or essentially 0.
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