Alan

Perhaps these graphs will help:

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What is the full question?  

You've forgotten one of the minus signs Guest #1

f'(x) = 0 - 10*(-2)e^-2x  or  f'(x) = 20e^-2x 

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"Twenty-five percent of all automobiles undergoing an emissions inspection at a certain inspection station fail the inspection. 

(d) What is the probability that among 25 randomly selected cars, the number that pass is within 1 standard deviation of the mean value?"

I've assumed a binomial distribution.  i.e. each car either passes or fails.

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n = b + r + y    n = total

b = 2r             twice as many black as red

y/n = 1/7       yellow probability

n = 3r + y

y/(3r + y) = 1/7

7y = 3r + y

6y = 3r

r = 2y

b = 4y

r/n = 2y/n = 2/7    probability of drawing a red

b/n = 4y/n = 4/7   probability of drawing a black

(I see Melody beat me to it.  Luckily, I got the same results as her!).

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You need to supply the table!!

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Try using the same approach as indicated here: https://web2.0calc.com/questions/math_76239#r1 

Testing:

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N/600 = 18/48

N = 600*18/48

N = 225

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The formulary (see very top of the page) can be useful here.  

https://web2.0calc.com/formulary/math/geometry/cylinder 

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