4 7 of students at a school are boys. If there are 2723 students at the school, how many are girls? 5 9 of students at a school
1 answer:
Answer:
1167 of them are girls in the first situation.
1052 of them are boys in the second situation.
Step-by-step explanation:
Since there are 2723 students at the school and 4/7 of them are boys, the number of boys:
→ 2723 x = 1556
The number of the girls = Total number of students - The number of boys
→ 2723 - 1556 = 1167
Since there are 2367 students at the school and 5/9 of them are girls, the number of girls
→ 2367 x = 1315
The number of the boys = Total number of students - The number of girls
→ 2367 - 1315 = 1052
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So
if you assume that the month has 30 days and that the library opens at midnight, then
24 hours in a day
5 pm=12+5=17 hours
on wednessday=17-2=15 hours
wednessday=1/7 of week
so we find 1/7 of 30 which is 30/7=4 and 2/7
then subtract that from 30
30-4 and 2/7=25 and 5/7
ok so then we have
25 and 5/7 days is 17 hours and
4 and 2/7 days is 15 hours
so just multipy them and add
25 and 5/7 times 17=437.143 hours
4 and 2/7 days times 15 =64.2857
add
437.143+64.2856=501.429
so aprox 501.429
the real equation is![[(\frac{1}{7})(n)(15)]+[ (\frac{6}{7}) (n)(17)]=hours](https://tex.z-dn.net/?f=%5B%28%5Cfrac%7B1%7D%7B7%7D%29%28n%29%2815%29%5D%2B%5B%20%28%5Cfrac%7B6%7D%7B7%7D%29%20%28n%29%2817%29%5D%3Dhours)
where n represents the number of days in the month
apros 501.429
if you assume that the month has 30 days and that the library opens at midnight, then
24 hours in a day
5 pm=12+5=17 hours
on wednessday=17-2=15 hours
wednessday=1/7 of week
so we find 1/7 of 30 which is 30/7=4 and 2/7
then subtract that from 30
30-4 and 2/7=25 and 5/7
ok so then we have
25 and 5/7 days is 17 hours and
4 and 2/7 days is 15 hours
so just multipy them and add
25 and 5/7 times 17=437.143 hours
4 and 2/7 days times 15 =64.2857
add
437.143+64.2856=501.429
so aprox 501.429
the real equation is
apros 501.429
Answer:
a) The best estimator for the population mean is given by the sample mean
b) The 99% confidence interval would be given by (4.969;6.431)
c) We are 99% confident that the true mean for th number of gallons of gasoline sold to his customers is between 4.969 and 6.431.
Step-by-step explanation:
1) Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
represent the sample mean for the sample
population mean (variable of interest)
represent the population standard deviation
n=45 represent the sample size
2) Part a
The best estimator for the population mean is given by the sample mean
3) Part b. Develop a 99 percent confidence interval for the population mean.
The confidence interval for the mean is given by the following formula:
(1)
Since the Confidence is 0.95 or 95%, the value of and
, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that
Now we have everything in order to replace into formula (1):
So on this case the 99% confidence interval would be given by (4.969;6.431)
4) Part c. Interpret the meaning of part (b).
On this case we can say this: We are 99% confident that the true mean for th number of gallons of gasoline sold to his customers is between 4.969 and 6.431.