A bag contains 5 blacks, 4 white and x red marble. If the probability of picking a red marble is $\tfrac{2}{5}$, find the value of x 

What is the probability that an integer x $(1\le x\le 20)$chosen at random is divisible by both 2 and 3

A box contains 5blue balls, 3 red balls and 2 white balls. Two balls were selected from the box with replacement. Find the probability of obtaining two blue or two red balls

Three boys shard some oranges. The first received $\tfrac{1}{3}$of the oranges and second received $\tfrac{2}{3}$ of the remainder. If the third boy received the remaining 12 oranges, how many oranges did they share?

A container  has 30 gold medals, 22 silver medals and 18 bronze medals. If one medal is selected at random from the container, what is the probability that it is not gold?

The unbiased die is rolled 100 times and the outcome is tabulated as follows

Some white balls were put in a basket containing twelve red balls and sixteen black balls. If the probability of picking a white ball from the basket is $\tfrac{3}{7}$, how many white balls were introduced.

Two dice are thrown. What is the probability that the sum of the number is divisible by 3

The probability of a students passing any examination is $\tfrac{2}{3}$. If the student takes three examination. What is the probability that he will not pass any of them