<h2>
Time required to complete the round trip 
where x is average velocity on the outgoing trip.</h2>
Step-by-step explanation:
Let average velocity of outgoing trip = x mph
The average velocity on the return trip is 15 miles per hour slower than the average velocity on the outgoing trip.
Average velocity of return trip = (x-15) mph
Distance to vacation place = 420 miles
Distance to vacation place = Time for outgoing trip x average velocity of outgoing trip
Distance to vacation place = Time for return trip x average velocity of return trip
We have total time T = t₁ + t₂
That is
Time required to complete the round trip where x is average velocity on the outgoing trip.
It has been a while since I had done these, but I believe you need to multiply all the measurements together
If you use the scientific notation to simplify these bigger numbers it will make it easier
Answer:
We need an SRS of scores of at least 153.
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 M as such
In which 
is the standard deviation of the population and n is the size of the sample.
How large an SRS of scores must you choose?
This is at least n, in which n is found when 
. So
Rounding to the next whole number, 153
We need an SRS of scores of at least 153.
