Answer:
67%
Step-by-step explanation:
There are a few methods to finding the percent of a number. You can use proportions:
The 'percent' is the percent of the fraction that you are looking for, or 48/72.
Cross-multiply: 72x = (48)(100) or 72x = 4800
Divide both sides by 72: 72x/72 = 4800/72
Solve for 'x': x = 66.6666...
Round 66.666.... to the nearest percent: 67%
Answer:
The 90% confidence interval for the mean score of all takers of this test is between 59.92 and 64.08. The lower end is 59.92, and the upper end is 64.08.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
So it is z with a pvalue of , so
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 62 - 2.08 = 59.92
The upper end of the interval is the sample mean added to M. So it is 62 + 2.08 = 64.08.
The 90% confidence interval for the mean score of all takers of this test is between 59.92 and 64.08. The lower end is 59.92, and the upper end is 64.08.