Answer:
12 hours
Step-by-step explanation:
Given data
Steve= 4 hours
Steve and Andrea= 3 hours
Applying the combined work formula
1/A+1/B= 1/T
1/4+1/B= 1/3
solve for B
B+4/4B= 1/3
cross multiply
3(B+4)= 4B
3B+12= 4B
12= 4B-3B
12= B
Hence Andrea will spend 12 hours alone
We did this same kind of problem in school. All we did was divide the those 2 numbers to figure out the unit price. So, 20/5 = 4 $ per CD.
<u>Given</u>:
Let the random variable x is normally distributed with mean
and 
We need to determine the probability of 
<u>Probability of </u>
<u>:</u>
The formula to determine the value of
is given by

Thus, we have;

Simplifying, we get;


Using the normal distribution table, the value of -2 is given by 0.0228

Thus, the value of
is 0.0228