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In a quiz, 12 students scored 5 each and 28 students scored 9 each.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In a quiz, students scored each and students scored each. A student says that the mean is , halfway between and . Is that right? Find the true mean.
Need a reminder? The key ideaShow
The mean is the total divided by how many values there are. Total = mean count.
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.
Step 1. Totals. and . Together, marks.
Step 2. Mean. marks.
Step 3. Why not 7? Halfway would be right only if the two groups were the same size. Here many more students scored 9, so the mean is closer to 9.
Answer: no; the mean is marks.
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