Please help me c: I will give you a super shiny medal!

Let S = {1,2,3,4,... 100} with each outcome having equal probability. What is the probability that a number picked at random is at least five.

Question

Please help me c: I will give you a super shiny medal!

Let S = {1,2,3,4,... 100} with each outcome having equal probability. What is the probability that a number picked at random is at least five.

lacris · Answer

First I know the equation is a compute at least probabilities:

1-P(none) ?

But the probability that none are 5 is: 100-5=95/100 = 0.95?
so it is:
1-P(0.95)?

What is P then?

lacris · Answer

(by none I meant the opposite of at least picking a 5)

welshfella · Answer

at leat picking a 5 means that the number picked is any number  from 5 to 100 ( including 5 and 100)

welshfella · Answer

* at least

holsteremission · Answer

The sample space $S$ follows a discrete uniform distribution, so each number $x$ has probability $p(x)=\dfrac{1}{100}$ of getting picked. This means the probability of selecting a number that is at least $5$ is
$$p(x\ge5)=\sum_{x=5}^{100}\frac{1}{100}=1-\sum_{x=1}^4\frac{1}{100}=1-p(x<5)$$

lacris · Answer

It was actually the classical method since all of them were equal probabilities, so:

P (at least 5) = 1- P ( 4 or less)
= 1-4/100
= 96/100

Thank you for helping, I asked my teacher this question and got this answer.