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 :)

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