There is a bag filled with 5 blue and 4 red marbles. A marble is taken at random from the bag, the colour is noted and then it is replaced. Another marble is taken at random. What is the probability of getting exactly 1 blue?

40/81.

Step-by-step explanation:

Prob(Picking a blue on one pick) = 5/(5+4) = 5/9.

Prob(Picking a red on one pick) = 4/(5+4) = 4/9.

Required probability  is either the first pick is blue OR the second pick is blue. (The other probability on one pick is of course a red marble.)

Probability of at least 1 blue = P(red)*P(blue) + P(blue)*P(red)

= 4/9 * 5/9 + 5/9*4/9

= 20/81 + 20/81

= 40/81.

Another way of solving this is by using a tree diagram.

47 - 90 = 43

43 - 180 = x

x = 137

"image"

step-by-step explanation:

in most of these problems, the notation is that the point with a "prime" is the image of the point without. that is, b' is the image of b.

here, there is no dilation or reflection. there is simply translation (with no direction shown). which figure you call the "preimage" and which one you call the "image" is up to you. as a matter of convention, the naming is as described above.