Average Test-6 (Calculating average Speed)

Answer: Option C

Explanation

Total distance rahul drives = 120+120=240 miles

Joe drives at two different speeds: 60 mph and 40 mph.

Time spent driving 60 mph = 120 miles/60 mph = 2 hours

Time spent driving 40 mph = 120 miles/40 mph = 3 hours

Average Speed = $\frac{240 \mathrm{miles}}{5 \mathrm{hrs}}=48 \mathrm{mph}$ = 48 mp

Hence, Option C is correct.

Answer: Option B

Explanation

According to the question

We now the formula,

Distance= speed×time

    =60×30 =1800 km/hr

Time =$\frac{\mathrm{distance}}{\mathrm{speed}}=\frac{1800}{40}$=45 hrs

Average speed =$\frac{\mathrm{Total} \mathrm{distance}}{\mathrm{Total} \mathrm{time} }$

$$\begin{gathered} =\frac{1800+1800}{30+45} \\ =\frac{3600}{75} \end{gathered}$$

Average= 48 km/hr

Hence,, Option B is correct.

Answer: Option A

Explanation

The distance covered by him is equal to 800 meters and he has completed it in 80 seconds.

We know the formula,

Average speed =$\frac{\mathrm{Total} \mathrm{distance}}{\mathrm{Total} \mathrm{time}}$

∴ Average speed of the runner during this lap=$\frac{800}{8}$

= 10 m/s

Hence, Option A is correct.

Answer: Option C

Explanation

Sunil travel 90 km in 9 hrs through cycle

To find the constant speed of Sunil,
According to the formula Speed= $\frac{\mathrm{Distance}}{\mathrm{Time}}$

Given,

Distance = 90 km and Time = 9 hrs.

Substitute both in speed formula.

=$\frac{90}{9}$= 9 km/hr

Hence, Option C is correct.

Answer: Option B

Explanation

Acccording to the question,

Total distance= 10 km+12 km =22 kms

Total time = $$\begin{gathered} =\left(\frac{10}{12}\right)+\left(\frac{12}{10}\right) \\ =\frac{100+144}{120} \\ =\frac{244}{120}\mathrm{hrs} \end{gathered}$$

Average speed

$$\begin{gathered} =\frac{{\displaystyle \left(\frac{22}{1}\right)}}{\left({\displaystyle \frac{244}{120}}\right)} \\ =\frac{22\times 120}{1\times 244}=\frac{11\times 120}{122} \\ =\frac{11+60}{61}=\frac{660}{61} \end{gathered}$$

= 10.8 kmph

Hence, Option B is correct.