Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

You are not logged in.

## #1 2012-11-23 12:25:19

infinitebrain
Member
Registered: 2008-07-01
Posts: 153

### Probability Question

Six boys and twelve girls are in a senior class.Half the boys and 25% of the girls wear glasses.What is the chosen probability that a student chosen randomly is a boy,wears glasses,or both? I know the answer is 50%, but could someone could explain to me clearly how you get that answer? Thanks!

The best thing about life is you don't know what to expect

Offline

## #2 2012-11-23 14:19:58

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,442
Website

### Re: Probability Question

Probability that the chosen one is a boy =

Probability that the chosen one wears glasses =

Probability that the chosen one is both a boy and wears glasses = (Probability of being a boy) * (Probability of a boy to wear glasses) =

Last edited by Agnishom (2012-11-23 14:22:47)

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

## #3 2012-11-23 14:35:03

infinitebrain
Member
Registered: 2008-07-01
Posts: 153

### Re: Probability Question

Thank you Agnishom!
Sorry, I went back to look at the documents and it said A is correct, which is 16 2/3%!

The best thing about life is you don't know what to expect

Offline

## #4 2012-11-23 14:41:15

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,442
Website

### Re: Probability Question

You are Welcome, @infinitebrain

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline