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
Relative frequency is the absolute frequency (i.e. the number of times of the wanted result) divided by the total number of events.
In this case you have to calculate: the number of heads that came up divided by the number of times the coin was flipped.
Number of times the coin was flipped: 20
Numbef of times head came up: 7
Relative frequency: 7 / 20 = 0.35, which is the option B.
Answer:
3/17 or 17.64%
Step-by-step explanation: