Practice | Hashtable

Home > Practice > Arithmetic Aptitude > Probability > Miscellaneous

1. An urn contains 6 red, 4 blue, 2 green 3 yellow marbles. If two marbles are drawn at random from the run, what is the probability that both are red ?

A. $\frac{1}{6}$

B. $\frac{1}{7}$

C. $\frac{2}{15}$

D. $\frac{2}{5}$

Solution:

Total number of balls = (6 + 4 + 2 + 3) = 15
Let E be the event of drawing 2 red balls.
Then, n(E)

=^{6} C_{2}

= \frac{6 \times 5}{2 \times 1}

= 15
Also,

n (S) =^{15} C_{2}

= \frac{15 \times 14}{2 \times 1}

= 105

∴ P (E) = \frac{n (E)}{n (S)} = \frac{15}{105} = \frac{1}{7}

You must login to add comments. Login now.