07 January 2022 Grouped data Objective Identify the

07 January 2022 Grouped data Objective • Identify the modal class. [Grade C] • Calculate an estimate of the mean from a grouped table. [Grade C] Task Key Words WS 1 Exam Qu 1 By Cang Tu Exam Qu 2

Key words • Grouped data Click here • Estimated mean Click here • Modal class When data is grouped into classes. If raw data is not given, the mean of that data is an estimated mean. The class that has the highest frequency. Click here WS 1 07 January 2022 By Cang Tu 1 st Slide

Worksheet 1 Ans 1 Grade C Qu 1 -2 Ans 2 Find the modal class and the estimated mean for each table 1) Modal class 2) 6 45 6 x 45 = 270 10 55 7 65 10 x 55 = 550 Estimated 7 x 65 = 455 mean 3 75 3 x 75 = 225 Total frequency = 26 Modal class 14 22. 5 14 x 22. 5 = 315 5 27. 5 5 x 27. 5 = 137. 5 3 32. 5 3 x 32. 5 = 97. 5 Total frequency = 22 07 January 2022 By Cang Tu Estimated mean Exam Qu 1 1 st Slide

Exam Qu 1 Ans 1 1) Caleb measures the heights of 30 plants The table gives some information about the heights, h cm, of the plants. Frequenc y, f 40 < ℎ ≤ 50 2 5 2 x 5 = 10 8 15 8 x 15 = 120 9 25 9 x 25 = 225 7 35 7 x 35 = 245 4 x 45 = 180 Total frequency = 30 Work out an estimate for the mean height of a plant Estimated mean 26 ………………. . cm (4 marks, C) Exam Qu 2 07 January 2022 By Cang Tu 1 st Slide

Exam Qu 2 Ans 2 a Ans 2 b 2) The table shows some information about the heights (h cm) of 100 students Frequency 160 < ℎ ≤ 170 8 125 8 x 125 = 1000 16 135 16 x 135 = 2160 25 145 25 x 145 = 3625 30 155 30 x 155 = 4650 21 165 21 x 165 = 3465 Total frequency = 100 a) Find the class interval in which the median lies 150 <ℎ ≤ 160 b) Work out an estimate for the mean height of the students Estimated mean 07 January 2022 (1 mark, C) (4 marks, C) By Cang Tu 1 st Slide