Frequency trees
The Maths Habit
Sort everyone in this room into two groups.
Then split each group into two again.
How could you do it?
The two branches add up to the box before.
Find the missing number.
- Frequency
- How many there are.
- Frequency tree
- A diagram that sorts a group into smaller groups. It shows how many are in each group.
30 students.
12 are girls.
5 of the girls walk.
10 of the boys walk.
- 1Put in the numbers.Each number goes in its shaded box.
- 2Take away from the box before.The two branches add up to the box before. 30 − 12 = 18.
40 children at a club.
15 are girls.
9 of the girls play chess.
12 of the boys play chess.
50 people on a bus.
20 are adults.
12 of the adults have a bag.
18 of the children have a bag.
40 children at a club.
15 are girls.
9 of the girls play chess.
12 of the boys play chess.
30 cakes.
10 are big.
4 of the big cakes have jam.
15 of the small cakes have jam.
40 children at a club.
15 are girls.
9 of the girls play chess.
12 of the boys play chess.
60 people at a show.
35 are adults.
20 of the adults clap.
15 of the children clap.
40 children at a club.
15 are girls.
9 of the girls play chess.
12 of the boys play chess.
45 pens in a box.
20 are blue. The rest are black.
15 of the blue pens work.
18 of the black pens work.
150 apples.
30 are red. The rest are green.
25 of the red apples are ripe.
10 of the green apples are ripe.
280 visitors.
45 are adults.
30 of the adults buy a drink.
20 of the children buy a drink.
336 books on a shelf.
16 are new. The rest are old.
6 of the new books are big.
12 of the old books are big.
30 students.
12 are girls.
5 of the girls walk.
10 of the boys walk.
- 1Put in the numbers.Each number goes in its shaded box.
- 2Take away from the box before.The two branches add up to the box before. 30 − 12 = 18.
- 3Read the answer.Find the box the question asks for.
60 people at a park.
25 are adults.
15 of the adults have a dog.
20 of the children have a dog.
40 trains.
30 are fast. The rest are slow.
6 of the fast trains are late.
2 of the slow trains are late.
60 people at a park.
25 are adults.
15 of the adults have a dog.
20 of the children have a dog.
50 students on a trip.
20 are girls.
14 of the girls bring lunch.
25 of the boys bring lunch.
60 people at a park.
25 are adults.
15 of the adults have a dog.
20 of the children have a dog.
70 plants.
30 are in the sun. The rest are in the shade.
5 of the sun plants do not flower.
8 of the shade plants do not flower.
60 people at a park.
25 are adults.
15 of the adults have a dog.
20 of the children have a dog.
90 people vote.
40 are men.
25 of the men vote yes.
30 of the women vote yes.
Answer sheet
Is it right?
Thumbs up: right. Thumbs down: wrong.
The two branches add up to the box before.
Right60 students. 25 are girls. So 45 are boys.
Wrong: 60 − 25 = 3530 boys. 12 of the boys walk. So 18 boys do not walk.
RightThe four end boxes add up to the total.
Right
40 students. 15 are girls. 9 girls and 10 boys walk. Pick a student at random. Find the probability they walk.
194050 cars. 20 are red. 8 red cars and 12 other cars are new. Draw the tree. How many cars are old?
3080 people. Half are adults. 10 adults and 25 children swim. How many do not swim?
45
36 students. 16 are girls. 10 girls walk. 12 boys walk. Complete the tree.
20, 6 and 850 cars. 30 are red. 18 red cars are new. 9 other cars are new. Complete the tree.
50, 30, 18, 9; 20, 12 and 1140 people. 15 have tea. The rest have juice. 10 juice drinkers have cake. How many juice drinkers have no cake?
15