How Do You Calculate the Probability of a Heart Attack in a High-Risk Group?

[Calculator14]

Homework Statement

In a certain high-risk group, the chance of a person having suffered a heart attack is 70%. If four persons are chosen from the group, find the probability that at least one will have had a heart attack.

Homework Equations

(work shown below) these would be dependent

The Attempt at a Solution

(.7)/(4) = 2.8

 

[daveb]

It might be easier to think of the chance that a specific individual doesn't have a heart attack, so what are the chances that none of the individuals have heart attacks (and you might want to rethink the dependence).

 

[the_amateur]

your answer is wrong
i don think it is a dependent event

the probability of a person with heart attack is 0.7

so the probability that among 4 at least 1 has heart attack = 1 - probability that none have

= 1 - (0.3)$^{4}$
must be correct but verify it

 

[Laiva-59]

Amateur's answer is correct.

Your attempt doesn't make any sense.
Remember: probability can never be more than 1.

So if you find 2.8, think again.