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)