These marbles are placed in a bag and two of them are randomly drawn.
What is the probability of drawing two pink
marbles if the first one is placed back in the
bag before the second draw?
Give your answer as a ratio, reduced to
simplest terms.
[?]
Hint: Multiply the probability of the 1st Event by the
probability of the 2nd Event to get your answer.
Enter

Explanation:

There are 3 pink marbles out of 10 total (we can see that 2 yellow + 3 pink + 5 blue = 10 total)

The fraction 3/10 represents the probability of pulling out a pink marble at random. Since the first one is put back, this means the fraction 3/10 stays the same on the second draw as well.

We use the idea mentioned in the hint to multiply the fractions:

(3/10)*(3/10) = (3*3)/(10*10) = 9/100

The probability of pulling two pink marbles in a row is 9/100, where the first marble is put back.

Effectively, if you were given 100 tries at doing this, you should expect about 9 of those times you get 2 pink marbles in a row.

(c, 0) i might be wrong so don't put full faith on my answer

there are lots of ways.   pick's theorem tells us if the vertices are lattice points the area a is

a = b/2 + i - 1

where b is the number of boundary lattice points and i is the number of interior lattice points.

in the figure i count b=16, i=50 so

a = 8 + 50 - 1 = 57

let's try the shoelace formula.   the area is half the sum of the cross products of the sides.  

a(-2,6)   -2(2)-6(-5) = 26

b(-5,2)   -5(-3) - 2(-2) = 19

c(-2,-3) -2(-3) - (-3)(4) = 18

d(4,-3)   4(3) - (-3)(5) = 27

e(5,3)   5(3) - 3(1) = 12

f(1,3)     1(6) - 3(-2) = 12

a(-2,6)

each of the cross products is twice the area of the triangle with the associated side and one vertex the origin. so the area of abo=26/2=13.

area = (1/2) (26 + 19 +   18 + 27 + 12 + 12) = 57

that checks!