Math homework on statistics . 8 questions

Question

Normal Curve 

1. A set of data has a normal distribution with

mean of 50 and a standard deviation of 5. 

Sketch and label a normal curve.

2. Find the probability that a randomly selected x-

value is between 45 and 60

3. Find the probability that a randomly selected x-

value is at least 60

4. Find the probability that a randomly selected x-value

is at most 50.



Confidence Interval 

Confidence Level

90%

95%

99%

Critical Value z*

1.645

1.96

2.576

5. Two-hundred and fifty randomly selected people

are surveyed to determine if they own a tablet. 

Of the 250 surveyed, 98 reported owning a

tablet. Find the 90 % confidence interval for the

people who own tablets.

6. You filled your car 100 times and found the mean

was 23.4 mpg with the standard deviation of .9

miles per gallon. Compute the 90% confidence

interval for your miles per gallon.

Do the results of problem #5 support that 42% of

people own a tablets? Why or why not.

(Hint use the results from #6 to determine) A

fuel-efficient four-wheel drive vehicle gets 24

mpg. Does this interval provide evidence that

your truck is fuel-efficient? Why or why not.

Answer 1

Pr(45<x<60)= .68/2+ .95/2= .34+47.5= 81.5%, using the empirical rule

Pr(x>60)= 2.5%

P(x<50)= 50%