ANSWER ASAP I HAVE A TEST ON IT

Question

An emergency life-support system has 4 batteries. the probability of any battery failing is 0.01. what is the probabilty that

(A) none fails?

(B) all fail?

(C) more than 2 fail?

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Answer 1

The assumption is that the failure of any battery is an independent event. For any combination of events, the probability is the product of the individual probabilities. For example, each time you flip a coin the odds of heads is 1/2. Flip 2 coins and the odds of 2 heads is 1/4.

The odds of something NOT happening is 1 - the odds that it WILL happen. Using the coin example again, the odds of getting 3 heads in 3 tosses is 1/8. That means the odds of NOT getting 3 heads is 7/8

One example with the batteries: If each one has a failure probability of 0.01, then it has 0.99 probability of NOT failing. So the probability of 4 NOT failing is 0.99⁴