Question

There is a bag with only red marbles and blue marbles.The probability of randomly choosing a red marble is 7/8.There are 56 marbles in total in the bag and each is equally likely to be chosen.Work out how many red marbles there must be.

Answer 1

Answer:

Therefore the number red marble in the bag is 49.

Step-by-step explanation:

Probability: The ratio of favorable out comes to the total outcomes.

$P=\frac{\textrm{Favorable outcomes}}{\textrm{Total outcomes}}$

Given that the probability of choosing of a red marble is $\frac78$ . There are 56 marbles in the bag.

Consider the number of marble be x.

Therefore, the probability of choosing of red marble is

$=\frac{\textrm{The number of red marble}}{\textrm{Total number of marble}}$

$=\frac{x}{56}$

According to the problem,

$\frac{x}{56}=\frac{7}{8}$

$\Rightarrow x=\frac78 \times 56$

$\Rightarrow x=49$

Therefore the number red marble in the bag is 49.