Question

A bag contains 10 white roses and y red roses. If the probability of selecting a white rose is $\frac{5}{8}$, then the number of red roses is

• A. 5
• B. 6
• C. 7
• D. 8

Answer 1

The correct option is B 6

Given that, a bag contains 10 white roses and y red roses.
$\therefore \text{Total number of roses}=10+y$
$\therefore \text{P(White rose)}=\frac{\text{Number of white roses}}{\text{Total number of roses}}$
$\Rightarrow \frac{5}{8}=\frac{10}{10+y}$
$\Rightarrow \frac{1}{8}=\frac{2}{10+y}$
$\Rightarrow 10+y=16$
$\Rightarrow y=6$
Thus, the number of red roses is 6.
Hence, the correct answer is option (b).