A box contains 40 pens. 30 of the pens are blue and the rest are green. one pen is taken out at random and replaced by five of the other colour. another pen is taken out at random. A. work out the probability that are 3 pens are green.
B. work out the probability that all three pens are the same colour.
C. work out the probability that all three pens on not the same colour. Help please​

B is the answer I believe.

Step-by-step explanation:

I think B

step-by-step explanation:

the true ones are a b and d

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240