Question

Please help me on Mathematics

Answer 1

Answer:

1. 20 km/h

2. 70 m/h

3. 6.5 h

4. 4.5 s

5. 184 km

Step-by-step explanation:

For first two questions, you can use the following formula:

$\displaystyle \large{s = \frac{d}{t}}$

I denote ‘s’ be speed, ‘d’ be distance and ‘t’ be time. Some books may use ‘v’ for speed instead of ‘s’ but I use ‘s’ variable instead so it makes the equation easier to memorize.

Therefore, speed = distance/time

( 1 ) The first question is given both distance be 60 km and time be 3 hours. Therefore:

$\displaystyle \large{s=\frac{60}{3}}\\\displaystyle \large{s=20 \ \ \sf{km / h}}$

So for the first question, the speed is 20 km/h

( 2 ) The second is given both distance be 140 m and time be 2 hours. Therefore:

$\displaystyle \large{s=\frac{140}{2}}\\\displaystyle \large{s=70 \ \ \sf{m / h}}$

Therefore, speed is 70 m/h

For the third and four questions, we will be finding time. From the speed formula:

$\displaystyle \large{s=\frac{d}{t}}$

Multiply both sides by t.

$\displaystyle \large{st=d}$

Divide both sides by s.

$\displaystyle \large{t=\frac{d}{s}}$

Therefore, time = distance/speed

( 3 ) The question is given speed be 40 km/h and distance be 260 km. Therefore:

$\displaystyle \large{t=\frac{260}{40}}\\\displaystyle \large{t=\frac{13}{2} \ \ \sf{h}}\\\displaystyle \large{t = 6\frac{1}{2} \ \ \sf{h}}\\\displaystyle \large{t= 6.5 \ \ \sf{h}}$

Therefore, time is 6.5 h

( 4 ) The question is given speed be 16 cm/s and distance be 72 cm. Therefore:

$\displaystyle \large{t=\frac{72}{16}}\\\displaystyle \large{t=\frac{9}{2} \ \ \sf{s}}\\\displaystyle \large{t=4\frac{1}{2} \ \ \sf{s}}\\\displaystyle \large{t=4.5 \ \ \sf{s}}$

Therefore, time is 4.5 s

For the last question, we have to find distance. From the speed formula:

$\displaystyle \large{s=\frac{d}{t}}$

Multiply both sides by t.

$\displaystyle \large{st=d}\\\displaystyle \large{d=st}$

Therefore, distance = speed * time

( 5 ) The question is given time be 4 hours and speed be 46 km/h. Therefore:

$\displaystyle \large{d=46 \cdot 4}\\\displaystyle \large{ d=184 \ \ \sf{km}}$

Therefore, distance is 184 km.

Answer 2

Answer:

1. 20 km/hr (60km / 3h)

2. 70 m/hr (170m / 2h)

3. 6.5 hr (260cm / 40km)

4. 4.5 s (72cm / 16cm)

5. 184 km (46km * 4h)

Step-by-step explanation:

We'll use d = distance, t = time, s = speed.

Speed over time can be found by dividing distance by time

s = d / t

We can take this formula and manipulate it to find either distance or time if we know two of the values. Keeping in mind division and multiplication cancel each other.

If we wanted to find d for instance we can multiply both sides by t to get

s * t = d

For time we can divide both sides of the above formula by s to get

t = d / s