A $1200 investment is made. How much should be invested at 15% and how much at 8% so that the total return on the entire investment is 9.5%?

The amount invested at 15% = $257.14

The amount invested at 8% = $942.86

Step-by-step explanation:

Let the amount invested at:

15% = a

8% = b

Total invesment = $1200

Hence:

a + b= $1200 Equation 1

a = 1200 - b

15% × a + 8% × b = 9.5% × 1200

0.15a + 0.08b = 0.095 × 1200

0.15a + 0.08b = 114 Equation 2

We substitute 1200 - b for a in Equation 2

0.15(1200 - b) + 0.08b = 114

180 - 0.15b + 0.08b = 114

- 0.15b + 0.08b = 114 - 180

- 0.07b = - 66

b = -66/-0.07

b = $942.85714286

Approximately = $942.86

Note that:a = 1200 - b

a = $1200 - $942.86

a = $257.14

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

the answer is b.)

< 1=< 2