For a given interest rate, simple interest varies jointly as the principal and time. If $3000 left in an account for 6 years earned interest of $1260, then how much interest would be earned in 7 years?
I sure hope that the above is not how "they" are teaching you to calculate simple interest
how about (7/6)1260 = 1470
To solve this problem, we can use the formula for simple interest, which is:
Interest = Principal * Rate * Time
First, let's find the rate by rearranging the formula:
Rate = Interest / (Principal * Time)
Given that $3000 left in an account for 6 years earned interest of $1260, we can substitute these values into the formula:
Rate = $1260 / ($3000 * 6)
Rate ≈ 0.07
Now we have the rate (0.07), and we can find the interest earned in 7 years using the same formula:
Interest = Principal * Rate * Time
Substituting the values into the formula:
Interest = $3000 * 0.07 * 7
Interest ≈ $1470
Therefore, the interest that would be earned in 7 years is approximately $1470.
I = k(P)(T) , compare with I = PRT, so k is jus like the rate R
given: when P = 3000, T=6, then I = 1260
1260 = k(3000)(6
k = 1260/( (3000)(6) ) = .07 , mmhhh, looks like we just found the interest rate
I = .07(P)(T)
so for the last part
I = .07(3000)(7) = 1470