The table of data shows the heights in centimetres of teachers at a school. Using a frequency table, find the number of teachers who are 175 centimetres or more.
There’re six rows and eight columns of numbers. Six multiplied by eight is equal to 48. Therefore, we have the height of 48 teachers. We could quite simply go along each row or column and find all the numbers that are 175 or greater. However, we were asked to use a frequency table. This means that we need to record the heights by splitting them into groups.
The shortest height was 155 centimetres. Therefore, a sensible way to split this data would be 155 to 164, 165 to 174, 175 to 184, 185 to 194, and all those numbers greater than 195. We know that, in total, there will be 48 teachers.
There were a total of 12 teachers whose heights were between 155 and 164 centimetres. 14 out of the 48 teachers had a height between 165 centimetres and 174 centimetres. There were nine teachers whose heights were between 175 and 184 centimetres. 10 of the teachers had a height between 185 and 194 centimetres. Finally, three of the teachers had a height equal to 195 centimetres. Therefore, in the final group, we have three teachers.
At this stage, it is worth adding our numbers as a check. We need to add 12, 14, nine, 10, and three. These five numbers add up to 48. Therefore, we have used every bit of data from the table. We were asked in the question to find the number of teachers who are 175 centimetres or more. This includes three of our groups: 175 to 184, 185 to 194, and 195 plus. We need to add nine, 10, and three to calculate the number of teachers who are 175 centimetres or more. Nine plus 10 is equal to 19. Adding three to this gives us 22.
This means that there were 22 teachers whose height was 175 centimetres or more.