JAMB - Mathematics (2018 - No. 54)
A box contains two red balls and four blue balls. A ball is drawn at random from the box and then replaced before a second ball is drawn. Find the probability of drawing two red balls.
\(\frac{2}{3}\)
\(\frac{1}{3}\)
\(\frac{1}{4}\)
\(\frac{1}{9}\)
Giải thích
Total number of balls = 2 + 4 = 6
P(of picking a red ball) = \(\frac{2}{6}\) = \(\frac{1}{3}\)
P(of picking a blue ball) = \(\frac{4}{6}\) = \(\frac{2}{3}\)
With replacement,
P( picking two red balls) = \(\frac{1}{3}\) × \(\frac{1}{3}\) = \(\frac{1}{9}\)