Answer:
there are 25 students in the class and 15 who wear glasses.
Base x height divided by 2
10x8=80
80÷2=40
area=40
39/500 needs to be multiplied by 15, which results in 585/500. This is 1.17 as a decimal. 191/200 in diameter needs to be multiplied by 8, which equals 1528/200. This is 7.64 as a decimal.
<span>So we need to see how does the decimal point change it's place in the quotient when we divide any number by increasing powers of 10. Lets start with number 1. The decimal point is: 1.0 and when we divide by 10^1=10 we get 1/10=0.1. The decimal point has moved one place to the left. Now lets divide 1 by 10^2 and we get 1/100=0.01. Again, the decimal point has moved one more place to the left. Now: 1/10^3 = 1/1000 = 0.001. Next would be 0.0001, next one would be 0.00001 and so on. </span>
