The table shows the marks of 40 pupils. Write the less than cumulative frequencies…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The table shows the marks of pupils.
| Marks | Pupils |
|---|---|
| 0-10 | 4 |
| 10-20 | 7 |
| 20-30 | 12 |
| 30-40 | 11 |
| 40-50 | 6 |
Write the less than cumulative frequencies. How many pupils scored less than , and how many less than ?
Need a reminder? The key ideaShow
The less than cumulative frequency of a limit counts the values below it and is plotted at the upper limit. The more than cumulative frequency counts the values above it and is plotted at the lower limit. At every limit, less than plus more than equals . The curves cross at the height , and the horizontal reading is the median.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Five classes of width , with .
Step 1. The running totals. , then , then , then , then .
Step 2. The table. Less than : . Less than : . Less than : . Less than : . Less than : .
Answer: pupils scored less than and pupils scored less than .
Check. The last total, , is the number of pupils.
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