Printable · GCSE Foundation · ages 14-16

Independent and dependent combined events worksheet — GCSE Foundation

Fifteen questions on "independent and dependent combined events" — DfE statement P8. Print it, or print three versions so neighbours cannot copy by letter; the key gives the letter for each version.

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Independent and dependent combined events worksheet — GCSE Foundation

Maths · GCSE Foundation · P8 · Independent and dependent combined events · 15 questions

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1.A fair spinner has 8 equal sections: 5 are red and 3 are blue. Freya spins it twice, and each spin is independent of the other. Work out the probability that she gets one red and one blue in the two spins, in either order.
(a)39/64
(b)15/32
(c)15/28
(d)15/64
2.A spinner has equal sections, and the probability that it lands on blue in a single spin is 1/4. It is spun twice, and the two spins are independent. Work out the probability that it lands on blue on both spins.
(a)1/16
(b)1/2
(c)1/4
(d)1/8
3.A fair coin is flipped three times. Work out the probability of getting at least one head.
(a)1/2
(b)1/8
(c)7/8
(d)3/8
4.Harry plays a game in which he flips a fair coin and rolls an ordinary fair dice. He wins a prize only if the coin shows heads and the dice shows a 6. Work out the probability that Harry wins a prize.
(a)2/3
(b)1/12
(c)1/6
(d)1/8
5.A drawer contains 4 red socks and 2 blue socks. Two socks are taken out at random, one after the other, without the first being put back. Work out the probability that both socks are the same colour.
(a)7/18
(b)2/5
(c)5/9
(d)7/15
6.A tree diagram shows two rounds of a game, played independently. On each round, the probability of losing is 0.7 and the probability of winning is 0.3. Work out the probability of losing both rounds.
(a)0.09
(b)1.4
(c)0.49
(d)0.7
7.The probability that Ben catches his bus on time is 0.8. The probability that Freya catches her bus on time is 0.5. The two events are independent. Work out the probability that both Ben and Freya catch their bus on time.
(a)0.3
(b)0.4
(c)1.3
(d)0.1
8.A fair spinner is divided into 5 equal sections, 2 labelled win and 3 labelled lose. Zara spins it twice, and the two spins are independent. Work out the probability that she wins on the first spin and loses on the second spin.
(a)9/25
(b)6/25
(c)4/25
(d)3/10
9.The probability that a seed fails to germinate is 1/5. Three seeds are planted independently. Work out the probability that at least one of the three seeds germinates.
(a)12/125
(b)4/5
(c)64/125
(d)124/125
10.On Amelia's walk to school there are two sets of traffic lights. The probability that the first set is green when she reaches it is 0.4. The probability that the second set is green when she reaches it is 0.5. The two sets work independently of each other. Work out the probability that both sets are green.
(a)0.2
(b)0.1
(c)0.45
(d)0.9
11.The probability that Leo wakes up before his alarm is 0.35. The probability that his younger sister wakes up before her alarm, independently of Leo, is 0.28. Work out the probability that neither of them wakes up before their alarm.
(a)0.098
(b)0.63
(c)0.532
(d)0.468
12.Five raffle tickets numbered 1 to 5 are in a bag. Two tickets are drawn one after the other and the first is not put back. Work out the probability that ticket 1 is drawn first and ticket 2 is drawn second.
(a)1/25
(b)1/20
(c)2/5
(d)1/10
13.The probability that Kofi passes his driving test on any attempt is 0.6, and each attempt is independent of the others. Work out the probability that he fails both his first two attempts.
(a)0.16
(b)0.36
(c)0.24
(d)0.4
14.A bag contains 5 red counters and 5 green counters. Three counters are taken out one at a time and are not put back. Work out the probability that all three counters are red.
(a)1/12
(b)3/50
(c)1/8
(d)2/9
15.Two events are independent. The first has probability 2/5 and the second has probability 1/3. Work out the probability that both events happen.
(a)1/15
(b)11/15
(c)2/15
(d)3/8

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