Juyi just got back from a 10 mile bicycle ride. if she had ridden 3 miles per hour faster, the ride would have taken her 30 fewer minutes. wat was her speed on the ride?

Step-by-step explanation:

Let her actual speed = r

Let her actual time = t

d = 10 in either case

Case 1

r*t = 10

Case 2

(r + 10)(t - 1/2) = 10 Note that 30 minutes = 1/2 hour. Remove the brackets

rt + 10t - (1/2) r - 5 = 10

rt = 10 from Case 1

10 + 10t - r/2 - 5 = 10        Subtract 10 from both sides

10t - r/2 - 5 = 0                 Add 5 to both sides

10t - r/2 = 5                      Let t = 10/r from the first equation

10*10/r - r/2 = 5                Simplify the left

100/r - r/2 = 5                   Multiply both sides by 2r

100*2r/r - 2r*r/2 = 5*2r    Simplify

200 - r^2 = 10*r                Subtract 10r from both sides.

-r^2 - 10r + 200 = 0          Use the quadratic formula

a = - 1

b = - 10

c = 200

I'll the quadratic solution to you. The two answers you get are

x1 = -20 (which cannot be used)

x2 = 10 which is the answer

So her rate was actually 10 miles / hour which is a pretty good clip for a bicycle.

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.

too hard the other guy did it

step-by-step explanation: