CPhill

It's like cards....once you lay them on the table....they're considered "played".....no "do-overs"

pi x r^2 = Area

pi x 2^2 = Area

pi x 4 = Area

12.57 units² = Area

Thanks for catching that typo Anonymous....I've fixed it now!!

(4000L / 6 hr) x (1 cubic m / 1000L) x (1 hr / 3600 sec)  = (1/5400)m³/sec = 0.000185m³/sec

My theory is......points awarded.....stay FOREVER !!!

The cosine of 60 = 1/2

So

1- 2 (1/2)^2 =

1 - 2 (1/4) = 1 - 2/4 =

1- 1/2 = 1/2

First multiply the wattage of the device times the hours it was in use. So we have:

350 x 6 = 2100

Divide this by 1000 = 2.1

This is the number of kilowatt hrs. used

Multiply this by .50 per kWh and we get

$1.05

(1 + 3/5)  + ( 2 + 1/5)

So, converting the mixed numbers to fractions, we have

8/5 + 11/5  =   19/5   = 3 + 4/5

If we're counting its drop as the first fall, we have

250(.6)(.6)(.6) = 250(.6)³ = 54 ft.

From the package, we can choose any 4 of the 10. Thus, we have C(10,4) =210 ways of choosing the wheels.

But this only answers part of the question. On the skates themselves, we have 4 ways to choose which wheel goes on first, 3 ways of choosing the next one to go on, 2 ways for the next, and 1 way for the last.

So, the total number of ways to fit the wheels to a skate are 4 x 3 x 2 x 1  = 24.

So, the total ways to select the wheels from the package, times the number of ways to fit them to a skate = 210 x 24 = 5040.

I think this is correct, but I'd like someone to "check" me!!