Abag had 3 pink marbles and 4 purple marbles find the probability of selecting 3 pink marbles without replacement

There are 7 marbles in the bag.
The probability of drawing a  pink one is (3/7) .

Then you have 1 pink one, and there are 6 marbles in the bag.
The probability of drawing a pink one is (2/6) .

Then you have 2 pink ones, and there are 5 marbles in the bag.
The probability of drawing a pink one is (1/5) .

The probability of all 3 draws being successful is

           (3/7) (2/6) (1/5)  =  6/210  =  1/35  =  about  2.86%  (rounded)

You have 2 sides that are 2 cms and you have 6 sides that are 1/2 cm and you have 4 sides that are 1 cm. the smallest sides are 1/2 the medium sized sides are 1 and the smallest are 1/2. so to find the perimeter you have to add them all up together so your answer will be 11 cm's