Two rectangles are similar. If their dimensions are 4 by 5 and y and 5, find the value fo y > 5
4 coins are labled as 2, 3, 4 and 5. When 2 coins are drawn without looking, what is the probability that their sum is greater than 8?
Let:
The ratio between and is
Then:
So we have to draw coins 4 and 5.
The probability of drawing 4 is
The probability of drawing 5 is
Multiply the events.
Probability that sum is greater than 8:
(By the way, if you draw the 5 first, its probability will be , and of course the probability of drawing a 4 would then be .