Basic Probability (CIE IGCSE Maths: Core)

A bag contains 20 balls.
5 of these balls are red.
A ball is picked at random from the bag.

On the probability scale, draw an arrow ( ) to show the probability that this ball is red.

COMMONWEALTH

Lindon picks a letter at random from this word.
Explain why the probability that he picks a letter M is not .

Tickets for athletics or swimming or hockey or diving are placed in a box.
A ticket is picked at random from the box.

Complete the table.

On any day, the probability that Marcus will get a seat on the school bus is 0.93 .

Write down the probability that he will not get a seat on the school bus today.

There are 200 school days in a year.

Work out the expected number of days in a year that Marcus will not get a seat.

Dan either walks or cycles to school.
The probability that he cycles to school is .

Write down the probability that Dan walks to school.

There are 200 days in a school year.

Work out the expected number of days that Dan cycles to school in a school year.

The probability that a sweet made in a factory is the wrong shape is 0.0028 .
One day, the factory makes 25000 sweets.

Calculate the number of sweets that are expected to be the wrong shape.

A bag contains 50 counters.
10 of the counters are red.
One of the counters is taken from the bag at random.

Draw an arrow () on the scale to show the probability that this counter is red.

Find the probability that the counter is not red.

A bag contains 20 bulbs.
8 are yellow, 5 are red, 4 are white and 3 are pink.
Sam takes one bulb at random.

Find the probability that the bulb he takes is

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The probability that it rains tomorrow is 0.35 .

Work out the probability that it does not rain tomorrow.

The diagram shows a fair 8-sided spinner.

The numbers on the spinner are 3, 4, 4, 7, 7, 7, 8 and 9.

The spinner is spun once.

Write down the probability that the spinner lands on

The spinner is spun 160 times.

Work out the expected number of times the spinner lands on the number 7.

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Marco has ropes of four different colours.
He takes a rope at random.

Complete the table.

A bag contains 6 blue counters and 2 red counters only.
A counter is taken from the bag at random.

Draw an arrow (↓) on the probability scale to show the probability of taking

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Another bag contains green counters and black counters only.
A counter is taken from the bag at random.
The probability of taking a green counter is 0.64.

Work out the probability of taking a black counter.

Records show that  of all mullet caught are underweight.

In one day, 168 mullet are caught.

Work out the expected number of mullet that are underweight.

Mei has two fair square spinners, A and B.
Spinner A is numbered 1, 2, 2, 4 and spinner B is numbered 3, 3, 4, 5.

She spins both spinners and adds the two numbers.

A bag contains 7 red discs, 5 green discs and 2 pink discs.

Helen takes one disc at random, records the colour and replaces it in the bag.
She does this 140 times.

Find how many times she expects to take a green disc.

The probability that Tommy has his calculator for his mathematics lesson is 0.4 .
There are 120 mathematics lessons in one year.

Work out an estimate of the number of mathematics lessons in one year that Tommy has his calculator.

Ethan has a box of toys.
He takes a toy at random.

Complete the table.

A box contains 3 blue pens, 4 red pens and 8 green pens only.
A pen is chosen at random from the box.

Find the probability that this pen is green.

A cube has only one of its six faces painted yellow.
This cube is rolled 240 times.

Work out the expected number of times that it lands on the yellow face.

The probability that Kim wins a game is 0.72 .
In one year Kim will play 225 games.

Work out an estimate of the number of games Kim will win.

A bag contains 6 green balls, 5 red balls and 3 blue balls only.
A ball is taken from the bag at random.

Find the probability that the ball is

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