20 and 28 can be divided by 4, so just take the 4 out so the answer should be 4(5x - 7)
Answer:
The cost of 15 liters is $31.50
Step-by-step explanation:
1. Find the price for 1 liter of petrol.
Divide the cost by the number of liters:
$14.70 / 7 = $2.10 per liter.
2. Multiply the price for 1 liter by the new number of liters, 15.
$2.10 per liter x 15 liters = $31.50
Answer: If the level of confidence is increased without changing the sample size then<em> </em><u><em>The margin of error will decrease because the critical value will decrease. The decreased margin of error will cause the confidence interval to be narrower.</em></u>
where;
<em>Margin of error = Critical value × Standard deviation</em>
<em>Here, it can be duly noted that Margin of error has a positive relation with critical value, i.e </em><u><em>The margin of error will decrease because the critical value will decrease.</em></u>
<u><em>whereas;</em></u>
The confidence interval is <em>the value ± the margin of error.</em>
<em>Therefore, </em><u><em>the decreased margin of error will cause the confidence interval to be narrower.</em></u>
Answer: 26.5cm2
Step-by-step explanation:
By assuming the standard deviation of population 2.2 the confidence interval is 8.67 toys,8.94 toys.
Given sample size of 1492 children,99% confidence interval , sample mean of 8.8, population standard deviation=2.2.
This type of problems can be solved through z test and in z test we have to first find the z score and then p value from normal distribution table.
First we have to find the value of α which can be calculated as under:
α=(1-0.99)/2=0.005
p=1-0.005=0.995
corresponding z value will be 2.575 for p=0.995 .
Margin of error=z*x/d
where x is mean and d is standard deviation.
M=2.575*2.2/
=0.14
So the lower value will be x-M
=8.8-0.14
=8.66
=8.67 ( after rounding)
The upper value will be x+M
=8.8+0.14
=8.94
Hence the confidence interval will be 8.67 toys and 8.94 toys.
Learn more about z test at brainly.com/question/14453510
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