Answer:
The probability that the household has only cell phones and has high-speed Internet is 0.408
Step-by-step explanation:
Let A be the event that represents U.S. households has only cell phones
Let B be the event that represents U.S. households have high-speed Internet.
We are given that 51% of U.S. households has only cell phones
P(A)=0.51
We are given that 70% of the U.S. households have high-speed Internet.
P(B)=0.7
We are given that U.S. households having only cell phones, 80% have high-speed Internet. A U.S household is randomly selected.
P(B|A)=0.8

Hence the probability that the household has only cell phones and has high-speed Internet is 0.408
Answer:
Streamers are $2.50 each
Balloons are $1.50 each
Step-by-step explanation:
Make a system of equations
3s + 15b = 30
2s + 4b = 11
Solve by elimination: multiply the top equation by 2 and the bottom equation by -3.
6s + 30b = 60
-6s -12b = -33
18b = 27
b = 1.5
Plug in 1.5 as b to find s
3s + 15(1.5) = 30
3s +22.5 = 30
3s = 7.5
s = 2.5
The streamers are $2.50 and the balloons are $1.50
The roof is Approximately 7 inches wide because 756/108=7