Answer:
3 ÷ 1/3 = 9
Step-by-step explanation:
= 3 ÷ 1/3
= 3/3 (3/1) ÷ 1/3
= 9/3 × 3/1
= 9/1
= 9
In a large population, 61% of the people are vaccinated, meaning there are 39% who are not. The problem asks for the probability that out of the 4 randomly selected people, at least one of them has been vaccinated. Therefore, we need to add all the possibilities that there could be one, two, three or four randomly selected persons who were vaccinated.
For only one person, we use P(1), same reasoning should hold for other subscripts.
P(1) = (61/100)(39/100)(39/100)(39/100) = 0.03618459
P(2) = (61/100)(61/100)(39/100)(39/100) = 0.05659641
P(3) = (61/100)(61/100)(61/100)(39/100) = 0.08852259
P(4) = (61/100)(61/100)(61/100)(61/100) = 0.13845841
Adding these probabilities, we have 0.319761. Therefore the probability of at least one person has been vaccinated out of 4 persons randomly selected is 0.32 or 32%, rounded off to the nearest hundredths.
Answer:27/220
Step-by-step explanation:
She must have 2 �1 coins and 1 50p coin.
She can choose the 2 �1 coins 3C2 = 3 ways.
For each of those 3 ways she can choose the
50p coin 9C1 or 9 ways.
That's 3�9=27 ways to get �2.50.
She can choose any 3 coins in 12C3 = 220 ways.
The desired probability is 27 ways out of
220 ways,or 27/220, or 13.5% of the time.
Alternatively, you can write radicals as rational exponents, so that you get
Then recalling that
, you have
