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ASHA 777 [7]
2 years ago
13

12. A cyclist travels 40 km at a speed of x km/h. Find the time

Mathematics
2 answers:
GREYUIT [131]2 years ago
7 0

Answer:

Step-by-step explanation:

distance = rate times time, so

           

           distance

time = --------------

               rate

Here the distance is 40 km and the rate is x.  Then

              40 km

time = --------------  =  (40/x) hr

             x km/hr

If the speed is reduced by 2 km/hr, we get:

              40 km                                            40 km                  40

time = -------------------------------  or time = ----------------------- = --------- hr

             (x km/hr - 2 km/hr)                      (x - 2) (km/hr)       x - 2

The difference between the times is:

 40          40

-------- - --------- = 1 hr          Solve this for the original speed, x

x - 2         x

40x - 40x + 80                                80

-----------------------  =  1 hr     or     ------------ = 1     or 80 = x^2 - 2x

     x(x - 2)                                     x(x - 2)

Rewriting this in standard quadratic form:  x^2 - 2x - 80 = 0

Here a = 1, b = -2 and c = -80, and so the discriminant b^2 - 4ac is:

(-2)^2 - 4(1)(-80) = 324

The solutions are:

   

      -(-2) ± √324       2 ± 18

x = -------------------- = ------------ = 1 ± 9, or 10 (discard the other root)

              2                      2

The original speed was 10 km/hr

Ket [755]2 years ago
4 0

the answer is 10 km/hr.

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A student on the track team runs 45 minutes each day as a part of her training. She begins her workout by running at a constant
jeka57 [31]

D = RT would be the fundamental equation to answer this, which is

Distance in D

Rate is R (speed)

It is now.

We can determine the individual distances for the two legs of the whole to determine the overall distance D.

Initial Leg:

R = 8

T = a

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What is the formula for rate and distance?

Use the formula d = st to determine speed, distance, or time. Distance is equal to speed multiplied by time. Given two known numbers, the Speed Distance Time Calculator can solve for the unknown sdt value.

Units of seconds (s), minutes (min), hours (hr), or hours, minutes, and seconds can be used to input or solve for time (hh:mm:ss). Time format shortcuts are shown below.

Use the formula d = st, or distance equals speed times time, to find the distance.

Distance Equals speed x time

Since both reflect a certain amount of distance per unit of time, such as miles per hour or kilometers per hour, rate and speed are comparable. If speed s and rate r are equal, then r = s = d/t. The corresponding formula is d = rt, which denotes Rate times time are equivalent to distance.

Distance = Rate x Time

Use the speed formula, s = d/t, which states that speed is equal to distance divided by time, to solve for speed or rate.

speed equals distance/time.

Use the time formula, t = d/s, which states that time is equal to distance divided by speed, to solve for time.

Time = Speed/Distance

Learn more about rate and distance brainly.com/question/1090517

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