Question

At dan's school,6 out of every 10 kids know how to swim. If there are 350 kids in his school,how many know how to swim?

Answer 1

If the ratio of kids who know how to swim is 6:10, that means that 60% of the schools population knows how to swim.  So you can multiply 350 by 0.60 to get 210 kids.  

You can show why the calculation is true since 6/10 = x/350.  We can say the two ratios are equal since 6/10 ratio holds true for every group of 10 that leading up to a total number of 350.  (you can have 35 groups of 10 each one having a 6 to 10 ratio.  (6/10)x(35/35)=210/350

Answer 2

210 because if you multiply 10 by 35 to get 350 you have to multiply 6 by 35 then you get 210