The table shows the number of days taken off work by 40 workers in a year. By constructing a frequency table or otherwise, calculate the number of workers who took 20 or more days off work.
We could quite simply go along each row or column and find all the numbers that are 20 or greater. As the question mentions a frequency table, we can construct one of these to make our data easier to deal with. We can split the numbers from the table into four groups: zero to nine, 10 to 19, 20 to 29, and 30 plus.
We know that in total there were 40 workers. Therefore, the four frequencies have to add up to 40. There were six workers that took between zero and nine days off work. 15 out of the 40 workers took between 10 and 19 days off work. There were 17 workers who took between 20 and 29 days off work. Finally, there were two workers who took exactly 30 days off work. So they need to go in the final group.
At this stage, it is worth checking that all four frequencies add up to 40. Six plus 15 plus 17 plus two is equal to 40. Therefore, we have used every number from the table. We were asked in the question to calculate the number of workers who took 20 or more days off. This is the end two groups from 20 to 29 and from 30 and above. This means that we need to add these two frequencies 17 and two. 17 plus two is equal to 19.
Therefore, there were 19 workers who took 20 or more days off in the year.