Mary can make a costume twice as fast as Sam can. If they both work together, they can make
it in 6 hours. How long will it take Mary to
make the costume if she works alone?

If she works alone, it will take Mary 9 hours to make the costume.

Step-by-step explanation:

The together rate is the sum of each separate rate.

In this problem:

Together rate: 1/6

Sam's rate: 1/x

Mary is twice as fast as Sam, so her rate is 2/x.

Then

Mary's rate

2/x = 2/18 = 1/9

If she works alone, it will take Mary 9 hours to make the costume.

126.66 m²

step-by-step explanation:

the pertinent area formula is a = πr², where r is the radius.

here, a = π(6.35 m)² = 40.32π, or approximately 126.66 m²