# Need help with this probability question (statistics)?

when four digits (between 0 and 9 inclusive) are randomly selected with replacement for a lottery ticket, none of the digits is a 7.

I need to provide a written description of the complement of the given event, then find the probability of the complement of the given event.

I already turned in the homework to the professor and got the wrong answer. I am just trying to correct it now.

I thought I had to multiply (1/10)(1/10)(1/10)(1/10). Is it supposed to be a 9 instead of a 1? or am I just stupid?

### 1 Answer

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• J. J..
Lv 7
5 years ago
Favorite Answer

The probability of not having a 7 for the first number = 9/10

Likewise for all the three subsequeny digits

Therefore the probability that you do NOT get a 7 = (9/10 * 9/10 * 9/10 * 9/10) = 0.6561

Therefore the COMPLEMENT = 1 - (9/10 * 9/10 * 9/10 * 9/10)

= 1 - 0.6561

= 0.3439

Answer = 0.3439 or 34 .39%

• J. J..
Lv 7
5 years agoReport

Thanks for best answer

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