C I’m pretty sure hope this helps
Answer:
(A) Your friend will save $282.
(B) Your friend will get 23.5% off the original price of the mattress.
Step-by-step explanation:
We first need to find out the price of the mattress after the 15% discount. Our first step is to find what 15% of 1,200 is. We can do this by multiplying the two numbers.
1,200 x 15% -----> 1,200 x 0.15= 180.
15% of $1,200 is $180.
Next subtract $180 from $1,200, which equals $1,020. We can now apply the 10% off internet coupon.
1,020 x 10% ------> 1,020 x 0.10= 102.
10% of $1,020 is $102.
Next we subtract $102 from $1,020 and we get $918, the final price of the discounted mattress.
We subtract to see how much money the friend saved.
$1,200 - $918= $282.
We can get the percentage by dividing $282 by $1,200.
282 / 1200= 0.235 decimal form ----> 23.5%
Answer:
34.87% probability that all 5 have a wireless device
Step-by-step explanation:
For each student, there are only two possible outcomes. Either they own a wireless device, or they do not. The probability of a student owning a wireless device is independent from other students. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
81% of students own a wireless device.
This means that 
If 5 students are selected at random, what is the probability that all 5 have a wireless device?
This is P(X = 5) when n = 5. So


34.87% probability that all 5 have a wireless device