Answer:
a) It can be used because np and n(1-p) are both greater than 5.
Step-by-step explanation:
Binomial distribution and approximation to the normal:
The binomial distribution has two parameters:
n, which is the number of trials.
p, which is the probability of a success on a single trial.
If np and n(1-p) are both greater than 5, the normal approximation to the binomial can appropriately be used.
In this question:

So, lets verify the conditions:
np = 201*0.45 = 90.45 > 5
n(1-p) = 201*(1-0.45) = 201*0.55 = 110.55 > 5
Since both np and n(1-p) are greater than 5, the approximation can be used.
Answer:
the amount left to spend is $740.77
Step-by-step explanation:
The computation of the amount left to spend is as follows:
= Each month payment - last month payment bills
= $2,185.76 - $73.49 - $897.19 - $474.31
= $740.77
Hence, the amount left to spend is $740.77
We simply deduct three amount bills from the each month payment