Answer:
$39
Step-by-step explanation:
The cost of the treat was $30, with the addition of a 10% sale tax and a 20% tip on the original $30.
So, total of (10 + 20) = 30% extra cost she has to pay on the original $30.
Hence, the total amount to be paid for the meal will be
dollars. (Answer)
Answer:
(0.869, 12.33104)
Step-by-step explanation:
N1 = 110
N2 = 225
S1 = 24.8
S2 = 25.8
Bar x1 = 169.9
Bar x2 = 163.3
Difference in mean = 169.9 - 163.3 = 6.6
We use the z score
Alpha = 0.05
Z critical value at this alpha level = 1.96
We find standard error
√s1²/n1+s2²/n2
= √(24.8²/110 + 25.8²/225)
= 2.9239
Confidence interval
6.6 +-1.96(2.924)
(6.6-5.73104, 6.6+5.73104)
= (0.869, 12.331)
Using the margin of error for the z-distribution, the sample sizes are given as follows:
a) 822.
b) 1068.
<h3>What is a confidence interval of proportions?</h3>
A confidence interval of proportions is given by:

The margin of error is given by:

In which:
is the sample proportion.
We have a 95% confidence level, hence
, z is the value of Z that has a p-value of
, so the critical value is z = 1.96.
Item a:
The estimate is of
, hence we solve for n when M = 0.03.





n = 821.2
A sample of 822 is needed.
Item b:
No prior estimate, hence
.





n = 1067.11
A sample of 1068 is needed.
More can be learned about the z-distribution at brainly.com/question/25890103
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