Homework

Data Analysis

1. Samuel threw a fair die a few times and recorded the number shown on the die after each throw. He recorded the results using a dot diagram as shown below.

(a) How many times did he throw the die?(b) Which number appeared most frequently on the die?

2. The dot diagram below shows the test results of 20 students.

(a) If the passing mark for the test was 6 marks, what percentage of students passed the test?

(b) Find the ratio of the number of students who scored 5 marks to the number of students who scored 8 marks.

3. A hotel carried out a customer feedback survey recently. The dot diagram below shows the number of compliments received each day.

(a) How many compliments did the hotel receive in total?(b) Find the average number of compliments received per day.

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4. The ages of 30 participants of a culinary competition were recorded in the following stem-and-leaf diagram.

Key: 2 | 8 means 28 years old

(a) What was the age of the youngest participant?(b) What was the age of the oldest participant?(c) How many participants were less than 35 years old?

5. The speeds of vehicles, in km/h, passing by a junction during a 10-minute period are recorded in the following stem-and-leaf diagram.

(a) How many vehicles passed by the junction during the 10-minute period?(b) Find the difference between the fastest speed and the slowest speed among the

vehicles.(c) What percentage of vehicles drove below the speed of 80 km/h?

6. 30 boys and girls ran a distance of 2.4 km and the time they took to complete the run are recorded in the following back-to-back stem-and-leaf diagram.

Key: 9 | 6 means 9.6 minutes

(a) Find the average time taken for the girls to complete the run.(b) Find the average time taken for the boys to complete the run.

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7. The number of hours that a group of 21 students spend exercising in a week is recorded as follows.

2 4 2 3 3 5 81 5 7 7 6 2 48 3 3 5 4 3 1

Find(a) the mean,(b) the median,(c) the mode.

8. The table below shows the number of game consoles owned by a group of 45 children.

Number of game consoles 1 2 3 4 5Number of children 18 13 3 9 2

Find(a) the mean,(b) the median,(c) the mode.

9. A group of 70 students were asked about the number of hours they spent surfing the internet during a weekend. The table below shows the results.

Number of hours 4 5 6 7 8 9 10Number of students 3 8 7 9 15 10 18

Find(a) the mean,(b) the median,(c) the mode.

10. The following given numbers are already arranged in ascending order:

13, 13, 16, 17, 18, x, 19, 20, 21, 21

If the median of the above distribution is 18.5, find the value of x.

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11. A survey was carried out to find out the weekly amount spent on petrol by a group of motorists in a week. The results are recorded in the table below.

Amount spent ($a) Number of motorists20 ≤ a < 30 230 ≤ a < 40 540 ≤ a < 50 950 ≤ a < 60 1560 ≤ a < 70 1770 ≤ a < 80 3180 ≤ a < 90 2790 ≤ a < 100 11

(a) How many motorists participated in the survey?(b) Calculate an estimate of the mean weekly amount spent.

12. The table below shows the number of stamps collected by a group of students.

Number of stamps Number of students0 ≤ x < 30 1930 ≤ x < 60 4460 ≤ x < 90 2290 ≤ x < 120 35120 ≤ x < 150 30150 ≤ x < 180 15

Calculate an estimate of the mean number of stamps collected by each student.

End of Homework

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