Simple interest , 750 principal, 11 years, total interest due 412.5, interest rate = ? %

The interest rate is 5%.

Step-by-step explanation

The appropriate formula to use here is as follows:

i = simple interest = p*r*t.  

Let's solve this for i:  divide both sides of the equation by p*t:

  i

= r

p*t

Subbing $412.5 for i, $750 for p and 11 yrs for t, we get:

$412.50

= 0.05.

($750)(11)

The interest rate is 5%.

36 girls

step-by-step explanation:

the 48 boys is 4 parts of the ratio

divide 48 by 4 to obtain one part of the ratio

= 12 ← 1 part of the ratio

3 parts = 3 × 12 = 36 ← number of girls