SOLUTION: A restaurant owner has researched his daily sales over the past year and found the mean daily sales to be $850, with a standard deviation of $325. Based upon the restaurant owner's

Algebra ->  Probability-and-statistics -> SOLUTION: A restaurant owner has researched his daily sales over the past year and found the mean daily sales to be $850, with a standard deviation of $325. Based upon the restaurant owner's      Log On


   

Question 388055: A restaurant owner has researched his daily sales over the past year and found the mean daily sales to be $850, with a standard deviation of $325. Based upon the restaurant owner's analysis:
a. what percent of daily sales are less than $600?
b. what percent of daily sales are between $700 and $1000?
c. what percent of sales are between $1000 and $1200
d. what amount of sales separates the top 10 percent from the lower 90 percent?

Any hlep will be greatly appreciated... I will do the $5 donation if this can be completed by today at 7CST. Thank you in advance
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Find the z scores.
z=%28x-mu%29%2Fsigma
a) z=%28600-850%29%2F325=-0.7692
Now find P%28x%3C600%29=P%28-0.7692%29
.
.
.
b) z%5B1%5D=%28700-850%29%2F325
z%5B2%5D=%281000-850%29%2F325
P%28700%3Cx%3C1000%29=P%28z%5B2%5D%29-P%28z%5B1%5D%29
.
.
.
c) z%5B1%5D=%281000-850%29%2F325
z%5B2%5D=%281200-850%29%2F325
P%281000%3Cx%3C1200%29=P%28z%5B2%5D%29-P%28z%5B1%5D%29.
.
.
d) P%28z%29=0.90
Working backwards, find the z score that give P%28z%29=0.90
z=1.281552
Now find the x value that gives you that z score.
z=%28x-850%29%2F325=1.281552
Now solve for x.