Sandra has $60 in a savings account. The interest rate is 5%, compounded annually.
1 answer:
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Answer:
P = 0.008908
Step-by-step explanation:
The complete question is:
The table below describes the smoking habits of a group of asthma sufferers
Nonsmokers Light Smoker Heavy smoker Total
Men 303 35 37 375
Women 413 31 45 489
Total 716 66 82 864
If two different people are randomly selected from the 864 subjects, find the probability that they are both heavy smokers.
The number of ways in which we can select x subjects from a group of n subject is given by the combination and it is calculated as:
Now, there are 82C2 ways to select subjects that are both heavy smokers. Because we are going to select 2 subjects from a group of 82 heavy smokers. So, it is calculated as:
At the same way, there are 864C2 ways to select 2 different people from the 864 subjects. It is equal to:
Then, the probability P that two different people from the 864 subjects are both heavy smokers is:
First of all, we can observe that
So the expression becomes
This means that the expression is defined for every
Now, since the denominator is always positive (when it exists), the fraction can only be positive if the denominator is also positive: we must ask
Since we can't accept 3 as an answer, the actual solution set is