#### Read Microsoft Word - Pictograms, Bar & Line graphs text version

Pictograms

A representation of numbers by pictures is called pictogram (pictograph or picture graph). In a pictogram, each picture or symbol stands for a certain number of the same item. The picture used usually design to reflect the item being compared. The key tells you what each picture stands for.

The pictogram below shows the number of students taking each type of transport to school.

What is the world population in 1650? How many more people are there in 1999 than in 1975?

Exercise A: 1. Some people are surveyed on their choice of drinks. The following pictogram shows the results of the survey.

a. b. c. d.

How many people are surveyed? How many more people chose coffee over tea? What percentage of the people liked hot chocolate? What percentage of the people did not choose milk as their choice?

2. A survey of how people travel to work was recorded. Mode of travel Number of people MRT 48 Walk 30 Taxi 9 Bus 36 Car 21 a. Draw a pictogram to represent the given data, using one picture to represent 6 people. b. Which mode of travel is the most commonly used? c. What is the total number of people involved in the survey? d. What fraction of the total number of people took a bus to work?

Bar graphs Drawing pictograms usually takes quite a bit of effort. Another way of illustrating results is to draw a bar graph (bar chart). A bar graph is statistical diagram which uses bars to represent the number of units (frequencies) of various items. In a bar graph: · A heading should be given · Axes must be labelled clearly · The widths of the bars must be equal · The lengths of the bars represent the frequencies · Bar graphs can be drawn either vertically (column graph) or horizontally. · Two or more categories of data drawn for comparison, called multiple bar graph.

Example: The two graphs below show the sales of a certain product for the months of January and February.

It is claimed that sales for February is twice that if January. Do you agree? Why and why not? Give reasons for your answer.

Exercise B: 1. Draw a column graph to show the population of different cities in the world. Using a scale of 1 cm to City Population in millions represent 1 million people Sydney 4.2 Shanghai Paris Auckland Montreal 12.6 8.8 1.2 11.9

2. A timber mill cut down the following number of tress during the period from April to September. Month Number of trees Using a scale of 1 cm to represent 50 trees, April 200 draw a column graph to show the given May 160 information. June 280 July August September 100 240 300

3. A shop collected information on how many of each type of CD were sold over a period of time. This information is shown in the column graph below. It shows the average number of CD sold each week. a. Which CD was the most popular? b. Which type of CD did the shop sell the least? c. How many classical CDs were sold on the average each week? d. How many "Female vocal" CDs were sold on the average each week? e. Which type of CD had an average sale of i. 27 copies, ii. 8 copies each week? f. On the average, how many CDs did this shop sell each week?

4. The following bar graph shows the total number f tickets sold for a concert. a. What is the total number of tickets sold? b. Calculate the total amount of money collected from the sale of tickets. c. If the seating capacity for the concert hall is 2000, find the percentage of the occupancy.

5. The bar graph shows the number of fruits a man sold in a week. a. If he had 150 papayas at first, how many papayas had he left? b. If he threw 32 rotten oranges away and had 128 oranges left, how many oranges did he have at first before the sale of his oranges? c. How many apples, oranges and pears did he sell altogether? d. If he sold each watermelon at $5.20, how much did he collect from the sale of his watermelons? 6. The following bar graphs show the sales of two types of novels in a bookshop.

a. In which year was the total number of novels sold the highest? b. Which type of novels shows a steady growth of sales? c. In which year was there the greatest difference in sales between the Chinese and the English novels?

Line Graphs Line graphs are usually used to represent changes in data over a period of time. In a line graph, the data is first represented by points, and then line segments are drawn to join the points. Generally, the horizontal axis is used as the time axis and the vertical axis is used to show changes in the other quantity. Example: A patient's temperature is taken every two hours. Time Temperature (°C) 0600 39.4 0800 39.8 1000 37.6 1200 38.1 1400 37.4 1600 37.4 1800 37.1 2000 36.9 2200 36.9

a. Plot the points on a graph. b. Draw a line graph. c. Estimate the patient's temperature at 1100 and at 1700.

It is reasonable to join the points and complete the line graph, because the patient's temperature at intermediate times can be estimated. 1. The patient's temperature at 1100 is estimated at 37.9°C and at 1700 is 37.3°C. In some line graphs, values along the lines themselves have no meaning; they can, however, show a trend.

Exercise C: 1. Nabil's savings account balance at the end of each month is given in the table. Month January February March April May June July August September October November December Balance ($) 120 91 84 101 160 252 326 69 75 195 211 72 Draw a line graph of the balance on Nabil's account. a. During which month did he withdraw most money? b. What was the increase in the balance from the end of February until the end of May? c. During which months did she spend more than she saved?

2. The temperature in a garden greenhouse was taken at hourly intervals, as shown in the table. Time 0700 0800 0900 1000 1100 1200 1300 1400 1500 1600 1700 1800 Temperature (°C) 21.5 21.7 22.6 23.4 25.9 26.6 23.3 23.5 24.2 23.0 22.2 21.8 a. Draw a line graph of the temperature through the day. b. Between which two times was the fall in temperature greatest? c. At what time, approximately, was the temperature 25°C and rising? d. Estimate for how long the temperature was above 25°C.

3. The following line graph shows the average (percentage) humidity per month for the town in Australia.

a. During which month is it the most humid? b. What was the average humidity in i. ii. May June

c. In which month(s) was the average humidity i. ii. 56% 52%

d. In which months was the average humidity the same?

4. The following multiple line graphs show the average monthly rainfall in millimetres in Singapore and Kuala Lumpur.

a. Which is the driest month in each city respectively? b. Which is the wettest month in each city respectively? c. What is the difference between the April rainfall in the two cities?

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