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.

the total estimated nappy use.=10,500,000

step-by-step explanation:

given that on an average the average baby uses 3528 napkins.

in a particular year 2014, the number of births were 299697 in new south wales.

rounding off the number of births to the nearest hundred thousand we have

no of birtsh = 300000

also rounding off the average usage to nearst thousand we get

average use of a baby = 3500

hence total number of nappy estimated to be used = 3500x300000

= 10,500,000

answer is 10,500,000 nappies