1. Interpreting Histograms LO: To be able to interpret histograms including finding averages

2. HISTOGRAMS EXAMPLE The histogram below gives information on the speed (mph) of cars on a motorway. Find the median class. Frequency = Frequency Density x Width Speed (mph) 0 ≤ x < 30 30 ≤ x < 50 50 ≤ x < 80 80 ≤ x < 120 Frequency 0.8 30 0.8 x 30 24 5.8 20 5.8 x 20 116 8.5 30 8.5 x 30 255 1.2 40 1.2 x 40 48 CF 24 140 395 443 Median = 221.5th value Median class = 50 ≤ x < 80

3. HISTOGRAMS EXAMPLE The histogram below gives information on the speed (mph) of cars on a motorway. Find the median class. Frequency = Frequency Density x Width Speed (mph) ≤ x < Frequency CF Median =

4. HISTOGRAMS 1) The histogram shows the distances walked by some ramblers on the Lake District at the weekend. (a) Draw a frequency table and find the median class for the distance walked by the ramblers. (b) How many ramblers were in the sample? Distance (m) 0 ≤ x < 1 1 ≤ x < 2 2 ≤ x < 5 5 ≤ x < 7 Frequency 4 x 1 4 1 x 3 3 4 x 3 12 3 x 2 6 CF 4 7 19 25 7 ≤ x < 10 6 31 2 x 3 Median = 31 2 th value = 15.5 th value Median class = 2 ≤ x < 5 Find the total of the frequency 31

5. 0.3 0.43 0.57 0.1

6. 8 14 24 16 7

7. 2) The histogram shows the heights of plants in a greenhouse at a local garden centre. (a) Draw a frequency table and find the median class for the height of plants in the greenhouse. (b) How many plants were in the sample? Height (cm) 0 ≤ x < 10 10 ≤ x < 30 30 ≤ x < 45 45 ≤ x < 70 Frequency 0.5 x 10 5 0.7 x 20 14 0.6 x 15 9 0.8 x 25 20 CF 5 19 28 48 70 ≤ x < 100 6 54 0.2 x 30 Median = 54 + 1 2 th value = 27.5 th value Median class = 30 ≤ x < 45 Find the total of the frequency 54 Histogram

8. 1) Estimate the mean for the histograms on the task. 2) Draw a frequency table and find the median class for the recorded speeds of care on a motorway. Speed (mph) 0 ≤ x < 30 30 ≤ x < 50 50 ≤ x < 80 80 ≤ x < 120 Frequency 30 112 255 48 CF 30 142 397 445 Median = 445 + 1 2 th value = 223 th value Median class = 50 ≤ x < 80 (a) 4.4 miles (b) 42.6 cm

9. The histogram shows the length of time it takes to sell houses on a estate. (b) Calculate the total number of houses that were sold. (2 marks) Frequency Density Time (months) (a) Find the median class time to sell a house on the estate. (3 marks) Time (months) 0 ≤ x < 2 2 ≤ x < 4 4 ≤ x < 8 8 ≤ x < 12 Frequency 1x2 2 7 x 2 14 10 x 4 40 8 x 4 32 CF 2 16 56 88 12 ≤ x < 24 72 160 6 x 12 Median = 160 + 1 2 th value = 80.5 th value Median class = 8 ≤ x < 12 Find the total of the frequency 160

10. Worksheet Answers