# Thread: 2 simple probability questions

1. ## 2 simple probability questions

 Expected Grade E.G E.G E.G Studied More Than 4 Hours A B C D YES 0.12 0.06 0.12 0.02 NO 0.13 0.21 0.26 0.08

a) this student studied more than 4 hours and expects a B
b) this student studied more than 4 hours or expects a B

this is what i got:

a) P=0.06
b) P=0.32

I thought question (a) was straightforward so I just assumed the probability would be same as the percentage of students thats studied more than 4 hours and expected a B which was 0.06

For question (b) I got P=0.32 by simplying adding all the percentages of students that studied more than 4hours which was 0.32 and because within the 0.32 percentage the students who expected B were included, I'd assumed we just leave it at 0.32.

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I just wanted to make sure if I answered them correctly, if not what did I do wrong :s

Thanks in advance for reading and helping

2. ## Re: 2 simple probability questions

Hey briankimmy.

The first one is correct but the second is not.

P(Studied for 4 hours OR Expects a B) = 0.12 + 0.06 + 0.12 + 0.02 + 0.21 in R gives:

> 0.12 + 0.06 + 0.12 + 0.02 + 0.21
[1] 0.53