**Calculating Expectation**

Starter

In a bag there are red and blue counters. The probability of selecting a red counter from the bag is 4 .

5

(a) If the bag contains 5 counters, how many are red?

(b) If the bag contains 10 counters, how many are red?

(c) If the bag contains 100 counters, how many are red?

(d) If there are 75 counters in the bag, how many are red?

Calculating Expectation

In a bag there are red and blue counters. The probability of selecting a red counter from the bag is 4

5

(a) If the bag has 85 counters in how many are red?

(b) If the bag has 130 counters in how many are red?

Example

For a particular set of traffic lights, the probability of encountering a red light is 0.3.

If 14760 cars pass the set of lights in a week, how many cars would you expect to have to stop at the red light?

L.O. - To use a probability to calculate the expected number of a particular result.

Main Activity

Complete the Red, Amber, Green Activity sheet.

Red - (1) 0.02 x 30000 = 600 toast

(2) 0.8 x 240 = 192 drawing pins

(3) 0.7 x 120000 = 84000 plants

Amber - (4) x 1300 = 52 planes delayed.

(5) (a) x 240 = 40 times.

(b) x 240 = 120 times.

(c) x 240 = 160 times

(d) x 240 = 80 times

Green - (6) (a) 0.111

(b) Cumulus - 110, Stratocumulus - 91

Stratus - 54, Altocumulus - 40, Cirrus - 18

Cirrocumulus - 7, Nimbostratus - 2

Cumulonimbus - 1

1

25

1

6

3

6

4

6

2

6

Dice of Ultimate Power

1) Give a key word for the lesson.

2) Summarise one key point for the

lesson.

3) Explain one thing you have learned this

lesson.

4) State one thing you still don't understand following this lesson.

5) Suggest one thing you would like to find out

based on this lesson.

6) Free choice from 1 to 5, or another you make

up.

Starter

In a bag there are red and blue counters. The probability of selecting a red counter from the bag is 4 .

5

(a) If the bag contains 5 counters, how many are red?

4

(b) If the bag contains 10 counters, how many are red?

8

(c) If the bag contains 100 counters, how many are red?

80

(d) If there are 75 counters in the bag, how many are red?

60

Example

For a particular set of traffic lights, the probability of encountering a red light is 0.3.

If 14760 cars pass the set of lights in a week, how many cars would you expect to have to stop at the red light?

0.3 x 14760 = 4428

Calculating Expectation

In a bag there are red and blue counters. The probability of selecting a red counter from the bag is 4

5

(a) If the bag has 85 counters in how many are red?

68

(b) If the bag has 130 counters in how many are red?

104

**Activities**

**Activity**

Answers

Answers

**Key**

Examples

Examples

Worked

Example

Worked

Example