Help me please find the radius. ​

a. There is nothing wrong with Mary's reasoning b. 2 water lilies.

Step-by-step explanation:

a. This is because, she reasons that if she doubles the amount of water lilies she buys, it would take half the time it takes to produce 10,000 lilies. So, there is nothing wrong with Mary's reasoning.

b. Since it takes 1 water lily to produce 10000 lilies in 20 days, 1 water lily will produce x lilies in 10 days.

So, x = 10000 × 10/20 = 5000 lilies

So, 1 water lily produces 5000 lilies in 10 days.

So, x water lilies will produces 10000 lilies in 10 days.

So x = 10000 × 1/5000 = 2 water lilies

So, 2 water lilies will produce 10000 lilies in 10 days.

So, Mary needs 2 water lilies so she can meet her goal of having the pond surface covered in 10 days.