When money is invested at 4.5% simple interest for 4 months, the interest is $75. Find the principal

$555.6

Step-by-step explanation:

Simple interest = Principal x Rate x Time

Principal = Interest/Rate x Time

From the question, interest = $75

Rate= 4.5%; 4.5/100= 0.045

Time= 4 months

Slot the values into the formula:

P= 75/0.045 × 4/12

= 75/0.135

P= $555.6

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4

the square root of 16 is 4.

4*4 = 16