Answer:
A sample of 499 is needed.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of 
, and a confidence level of 
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of 
.
The margin of error is given by:
In this question, we have that:
90% confidence level
So 
, z is the value of Z that has a pvalue of 
, so 
.
How large a sample would be required in order to estimate the fraction of tenth graders reading at or below the eighth grade level at the 90% confidence level with an error of at most 0.03
We need a sample of n, which is found when 
. So
Rounding up
A sample of 499 is needed.
Well if it pumps 4 2/5 per minute that is equal to 4 4/10 in a minute or 4.4 because you multiply the top and bottom of the fraction by two. it’s still the same fraction but it is easy to convert to a decimal now. you could use this fraction but it’s much easier to use decimals. Because the first number is a decimal you should make the second one a decimal too. To do this you need to know that 1/4 of 100 is 25. so now we have these numbers and all you do now is divide 17.25 by 4.4 which could be rounded to 4 because it’s a long decimal
Answer:
182 seconds
Step-by-step explanation:
Given:
Time taken for first lap is 50 seconds and each subsequent lap takes 20% longer than previous
Solution:
Time taken for first lap = 50 sec
For second lap
Each subsequent lap takes 20% longer than previous
Previous lap time = 50 sec
second lap = 50 + 20% of 50
second lap 
second lap 
second lap 
For third lap
Each subsequent lap takes 20% longer than previous
Previous lap time = 60 sec
Third lap = 60 + 20% of 60
Time taken for 3 laps is equal to sum of all three laps time.
Therefore, it takes 182 seconds (3 min, 2 seconds) to run three laps
