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1. x = cost of one adult ticket
y= cost of one child ticket
2x+3y=31.60
x+2y=18.60 l multiply by -2
2x+3y=31.60
-2x-6y=-37.2
-3y=-5.6
y=1.87
2x+3(1.87)=31.60
2x+5.6=31.60
2x=31.60-5.6
2x=26
x=26/2
x=13
Answer: The adult ticket is $13 and the child ticket is $1.87
Using the z-distribution, a sample size of 180 is needed for the estimate.
<h3>What is a z-distribution confidence interval?</h3>
The confidence interval is:
The margin of error is given by:
In which:
is the sample mean.
is the standard deviation for the population.
In this problem, we have a 98% confidence level, hence
, z is the value of Z that has a p-value of 
, so the critical value is z = 2.327.
The population standard deviation is of 
, and to find the sample size, we have to solve for n when M = 4.
Hence:
n = 179.03.
Rounding up, as a sample size of 179 would result in an error slightly above 4, a sample of 180 is needed.
More can be learned about the z-distribution at brainly.com/question/25890103
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Answer:
x=3, y=1
Step-by-step explanation:
2x+y =7
3x-4y =5
Multiply the first equation by 4 so we can eliminate y
4(2x+y =7)
8x +4y =28
Add this to the second equation
8x +4y =28
3x-4y =5
----------------
11x = 33
Divide by 11
11x/11=33/11
x=3
Now we still need to find y
2x+y=7
2(3)+y =7
6+y=7
Subtract 6 from each side
6-6+y=7-6
y= 1
