The number of unread emails in Bryan’s account is 100. This number grows by 15 unread emails a day. The function N(t)=100+15t represents the relation between the number of unread emails, N, and the time, t, measured in days.

Independent variable = t

Dependent variable = N

Step-by-step explanation:

Given that the function N(t)=100+15t represents the relation between the number of unread emails, N, and the time, t, measured in days

The independent variable is an input which can be controlled. In the function

N(t)=100+15t

The independent variable is t

While the dependent variable is the output of a function when independent variable has been substituted.

In the function N(t)=100+15t

The number of unread messages depends on the number of time t measured in days as the number of unread messages N is a function of t.

Therefore, the independent variable is N.

answer: c, the green line

step-by-step explanation:

there is no black line, eliminate b.

simple interest implies periodic payments, but the red line shows no payments, eliminate d.

simple interest has equal payments. if paid say every day, the graph is about a straight line (actually a stairstep).

the yellow line is not straight, eliminate a.

check: the green line is straight, answer is c.

simple interest with positive interest rate gives a straight line sloping up to the right. green line:

g(t) = $100 + ($200-$100) ÷ (20 years) × (t years)

= $100 + (4%/year) × ($100)(t years)

incidentally, the yellow line curving upward represents continuously compounded interest

y = $100 × 2^(t years / (14 assuming the yellow line hits $200 at 14 years. 2^0 is 1, so y(0) = $100; 2^(14/14) is 2, so y(14) = $200.