# Math Help - [SOLVED] Probability

1. ## [SOLVED] Probability

A list of numbers consists of p positive and n negative numbers. If a number is picked at random from this list, the probability that the number is positive is (3/5). What is the value of (n/p)?

a) 3/8
b) 5/8
c) 2/3
d) 3/2
e) 8/3

- - - -521

2. Originally Posted by fabxx
A list of numbers consists of p positive and n negative numbers. If a number is picked at random from this list, the probability that the number is positive is (3/5). What is the value of (n/p)?

a) 3/8
b) 5/8
c) 2/3
d) 3/2
e) 8/3

- - - -521
$\frac{p}{p+n} = \frac{3}{5} \Rightarrow \frac{\frac{p}{n}}{\frac{p}{n} + 1} = \frac{3}{5} \, ....$

3. Originally Posted by mr fantastic
$\frac{p}{p+n} = \frac{3}{5} \Rightarrow \frac{\frac{p}{n}}{\frac{p}{n} + 1} = \frac{3}{5} \, ....$
Why $\frac{p}{p+n} = \frac{3}{5}$? Thanks

4. Originally Posted by fabxx
Why [tex]\frac{p}{p+n} = \frac{3}{5} ? Thanks
Number of positive numbers divided by the total number of positive and negative numbers.