The first step is finding out what percentage of the first sample eat at school. Out of 60 students surveyed, 40 eat school lunch. To find that percentage:
40 / 60 = 0.67 or 67% (approximately)
Now, we need to that that information and plug it into our problem. If we know 67% of kids eat school lunch, and 560 lunches were sold, we know that 560 is 67% of the school population. So now we must work backwards to find our answer.
To find out what 560 is 67% of, you will divide .67 by 560. This will get you approximately 836 < this is the number of students in total.
Answer: You can predict there are around 836 students in the school.
Whenever you work backwards like this, it's always good to check your answer. We can do so by seeing what 67% of 836 is by multiplying the two. Once done, you should get 560.12, which verifies our answer is correct.
