As per the problem
Jing spent 
of her money on a pack of pens.
of her money on a pack of markers.
and 
of her money on a pack of pencils.
Total fraction of money spent cab be given as below
Fraction of Money Spent =
Take the LCD of denominator, we get LCD of (3,2,8)=24
Fraction of Money Spent =
The mean and standard deviation of the scores are 75 and 9.5 respectively.
The z-score is a means to find the probability of getting a particular score. This is calculated to be:
where x is the score, μ is the mean, and σ is the standard deviation.
To be a part of the top 2.5 percent, the probability is:
The z-score for this probability, that is, P
12n+32=10n+20
-10n -10n
2n+32=20
-32 -32
2n= -12
2 2
N = -6
the probability that if you pick only one, it's defective, is 250/6700
Therefore, the probability that one is not defective is 6450/6700
a. You want all 4 to not be defective: (6450/6700)^4
b. all 100 have to be not defective: (6450/6700)^100
If you type this into a calculator, you will get about 0.022, so a probability of 2 % that all of them are not defective. As this is a very small probability, the outlet should plan with returned tires.
