Recap and sample data sets

Data set 4: global temperature

The mean global temperature from 1861 to 1996 is listed in [link] . The data, obtained from (External Link) , was converted to mean temperature in degrees Celsius.

Data set 5: price of petrol

The price of petrol in South Africa from August 1998 to July 2000 is shown in [link] .

Grouping data

One of the first steps to processing a large set of raw data is to arrange the data values together into a smaller number of groups, and then count how many of each data value there are in each group. The groups are usually based on some sort of interval of data values, so data values that fall into a specific interval, would be grouped together. The grouped data is often presented graphically or in a frequency table. (Frequency means “how many times”)

Exercises - grouping data

1. The height of 30 learners are given below. Fill in the grouped data below. (Tally is a convenient way to count in 5's. We use llll to indicate 5.)

   142	163	169	132	139	140	152	168	139	150
   161	132	162	172	146	152	150	132	157	133
   141	170	156	155	169	138	142	160	164	168

   Group	Tally	Frequency
   130 $\le h<$ 140
   140 $\le h<$ 150
   150 $\le h<$ 160
   160 $\le h<$ 170
   170 $\le h<$ 180

2. An experiment was conducted in class and 50 learners were asked to guess the number of sweets in a jar. The following guesses were recorded.

   56	49	40	11	33	33	37	29	30	59
   21	16	38	44	38	52	22	24	30	34
   42	15	48	33	51	44	33	17	19	44
   47	23	27	47	13	25	53	57	28	23
   36	35	40	23	45	39	32	58	22	40

   Draw up a grouped frequency table using intervals 11-20, 21-30, 31-40, etc.