On a certain hot summer day,223 people used the public swimming pool.the daily prices are 1.25 for children and 2.00 for adults.the recei
pts for admission totaled 431.50.how many children and how many adults swam at the public pool that day?

Probability of red is, P(R)=0.3
Probability of not red, P(R')=0.7

Possible outcomes with three reds are
R R R R' = 0.3×0.3×0.3×0.7 = 0.0189
R R R' R = 0.3×0.3×0.7×0.3 = 0.0189
R R' R R = 0.3×0.7×0.3×0.3 = 0.0189
R' R R R = 0.7×0.3×0.3×0.3 = 0.0189

Probability of getting exactly three marbles is = 4×0.0189 = 0.0756 = 7.56%