SOLUTION: Here is a tricky word problem that I hope I can get some help with from an expert here: T varies jointly as r and Bsquared. When r=7 and B=6, T=1008. Find T when r is 10 and 8 i

Question 1137780: Here is a tricky word problem that I hope I can get some help with from an expert here:
T varies jointly as r and Bsquared. When r=7 and B=6, T=1008. Find T when r is 10 and 8 is 12.
(T=4rB squared is not it)
Thank you.
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39620) (Show Source): You can put this solution on YOUR website!
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T varies jointly as r and B squared. When r=7 and B=6, T=1008. Find T when r is 10 and 8 is 12.
(T=4rB squared is not it)
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------------this is what the first sentence means, using k as variation constant.

-----------the value for k, using the given data.

This is the formula you need.

--
Did you really have r squared AND B squared ? If you did, then now you know what to do.
(Best bet that r is not squared.)

Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

You say T = 4rB^2 "is not it".

That's because that answer is a formula for calculating T from r and B; but the problem didn't ask for a formula. It asked for the new value of T given new values of r and B.

You can get the answer by plugging the new values in the formula.

However, since the problem only asks for the value of T with new values of r and B, there is no need to find a general formula. You can get the answer just by using the stated joint variation to see how the given value of T changes when the values of r and B change.

The given value of r is 7; the new value of r is 10. Since T varies directly as r, the new value of r multiplies the given value of T by 10/7.

The given value of B is 6; the new value of B is 12. Since T varies directly as the square of B, the new value of B multiplies the given value of T by (12/6)^2 = 2^2 = 4.

So the new value of T is

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