We have been given for a normal distribution the mean time it takes to walk to the bus stop is 8 minutes with a standard deviation of 2 minutes. And the mean time it takes for the bus to get to school is 20 minutes with a standard deviation of 4 minutes.
(a) Average time that it would take reach school can be obtained by adding the average times.
8+20 = 28 minutes.
(b) Standard deviation of the trip to school can be found as:

Therefore, standard deviation of the entire trip is 4.47 minutes.
(c) Let us first find z score corresponding to 30 minutes.
We need to find the probability such that 
Therefore, the required probability is 0.67.
(d) If average time to walk to school is 10 minutes, then overall average time for the trip will be 10+20 = 30 minutes.
(e) Standard deviation won't change it will remain 4.47
(f) The new probability will be:


Therefore, probability will be 0.50.
The Ostrich will take 64 minutes to cover 40 miles.
Data;
- rate = 25 miles in 40 minute
<h3>Rate</h3>
To calculate the time it will take the ostrich to cover 40 miles, we have to compare it with the rate (speed).

Cross multiply both sides

simplify the value

divide both sides by the coefficient of x

From the calculations above, it would take the ostrich 64 minutes to cover 40 miles.
Learn more on rates here;
brainly.com/question/8728504
*GUARANTEED ANSWER ✅*
Down below is the equation graphed
So Sahra is 3 times as old as her daugter. That means that the sum of their age is the daughters age times 4.
We can prove that by saying the daughters age is x. Sahra's age must be 3x. Their sum must be x+3x = 4x.
So to get the daughters age we divide the sum by 4, which is 8.
Five times x plus seven equals eighteen