Answer:
a) 
With:


b) 

c) 

d) 


Step-by-step explanation:
For this case we know the following propoertis for the random variable X

We select a sample size of n = 81
Part a
Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

With:


Part b
We want this probability:

We can use the z score formula given by:

And if we find the z score for 89 we got:


Part c

We can use the z score formula given by:

And if we find the z score for 75.65 we got:


Part d
We want this probability:

We find the z scores:



The cost is £79.76. Since the car covers 560 miles and 34.5 miles is travelled by one gallon. So, dividing 560 by 34.5 we get 16.23. Since 1 gallon is 4.55 litres, 16.23 gallons is 73.8465. Now the cost of petrol is £1.08 per litre. So, multiplying 73.8465 by £1.08 we have £79.76
I’m not sure sorry also it past due
Answer:
29.27% probability that it takes Ariana between 58 and 70 seconds to do a math problem
Step-by-step explanation:
An uniform probability is a case of probability in which each outcome is equally as likely.
For this situation, we have a lower limit of the distribution that we call a and an upper limit that we call b.
The probability that we find a value X between c and d, d being greater than c, is given by the following formula:

Uniformly distributed between 38 seconds and 79 seconds.
This means that 
What is the probability that it takes Ariana between 58 and 70 seconds to do a math problem


29.27% probability that it takes Ariana between 58 and 70 seconds to do a math problem
The complete question is
"The ratio table below shows the relationship between the number of packages of gum and the total pieces of gum.
Gum Packages of gum Pieces of gum
1
15
2
30
3
45
4
?
How many pieces of gum are in 4 packages of gum?"
Using a proportional function, there are 60 pieces of gum in 4 packages.
<h3>What is a proportional relationship?</h3>
Two values x and y are said to be in a proportional relationship if x=ky, where x and y are variables and k is a constant.
The constant k is called constant of proportionality.
The constant is given by:
k = 15/1
k = 30/2
k = 45/3
k = 15.
Therefore, the number of pieces of gums in x packages is given by:
y = 15x.
In 4 packages:
y = 15 x 4
y = 60 pieces of gum.
Using a proportional function, there are 60 pieces of gum in 4 packages.
More can be learned about proportional functions at brainly.com/question/10424180
#SPJ1