15% of the students at Dan´s school travel to school by bus. If there ae 300 students at his school, how many come by bus?
45 (make it easy... 10% of 300 is 30, half of 30 is 15, so 30 + 15 = 45)
20
One third of a cake is shared between 3 children. What fraction of the whole cake do they each get?
1/9 (make it easy...whole cake ÷ 3, each portion ÷ 3, 3 x 3 = 9)
15
Tim has 10 balls in a box. 5 are red, 3 are white, 2 are black. Without looking, what is the percentage of probability that the ball he takes out is black??