Probability Toolkit Practice Questions

Choose the word from the box below that best describes the probability that Sarah takes a blue bead.

impossible	unlikely	even chance	likely	certain

On the probability scale, mark with a cross ($\times$) the probability that Sarah takes a green bead.

On the probability scale, mark with a cross ($\times$) the probability that Sarah takes a red bead.

Write down the probability that Harry takes a banana.

Write down the probability that Harry does not take an apple.

The probability that Amir will be late for school tomorrow is $0.15$.

Work out the probability that Amir will not be late for school tomorrow.

Priya plays one game of chess.

The probability that Priya will win the game is $\frac{3}{8}$.

Work out the probability that Priya will not win the game.

Work out the probability that the spinner lands on yellow.

Jamal has three cards. Each card has a number on it.

2	5	7

Jamal puts two of the cards side by side to make a two-digit number.

List all the possible two-digit numbers he can make.

Write down the probability that a sunflower seed will not grow.

Farid plants 400 sunflower seeds.

Work out an estimate for the number of these seeds that will not grow.

Work out the relative frequency of the spinner landing on C.

Give your answer as a decimal.

Lena is going to spin the spinner 400 times.

Work out an estimate for the number of times the spinner will land on B.

Kim spins the same spinner 500 times and uses her results to estimate the probability that the spinner lands on A.

Whose results, Lena's or Kim's, will give the better estimate of this probability?
Give a reason for your answer.

Complete the sample space diagram to show all the possible totals.

Spinner A $\downarrow$ / Spinner B $\rightarrow$	1	2	3	4
1	2	3
2	3			6
3

Work out the probability that Sam's total is 5.

Work out the probability that Sam's total is a multiple of 3.

There are only red pencils, green pencils and blue pencils in a pot.

A pencil is taken at random from the pot.

The probability that the pencil is red is $0.4$
The probability that the pencil is green is $0.25$

There are 14 blue pencils in the pot.

Work out the total number of pencils in the pot.

Work out the probability that the dice lands on an even number or on the number 7.

Mo says

"The probability that the dice lands on an even number or on a multiple of 3 is $\frac{8}{10}$, because $\frac{5}{10}+\frac{3}{10}=\frac{8}{10}$"

Mo is not correct.

Explain why, and write down the correct probability.

Work out the relative frequency of the spinner landing on 3.

Do Joe's results suggest that the spinner is biased?
You must give a reason for your answer.

A counter is taken at random from the bag.

Work out the probability that the counter is green.

A counter is taken at random from the bag, its colour is recorded and the counter is put back in the bag.

This is done 260 times.

Work out an estimate for the number of times a blue counter is taken.

Work out the value of $x$.

The spinner is spun 400 times.

Work out an estimate for the number of times the spinner lands on an even number.