$A$ man walks at the rate of $5 \, km/hr$ for $6 \, hours$ and at $4 \, km/hr$ for $12 \, hours$. The average speed of the man (in $km/hr$) is:

The speeds of $A$ and $B$ are in the ratio of $3: 4$. $A$ takes $20 \, min$ more than $B$ to reach a destination. Find the time in which $A$ reaches the destination.

The speed of a train going from Nagpur to Allahabad is $100 \text{ km/h}$,while its speed is $150 \text{ km/h}$ when coming back from Allahabad to Nagpur. What is the average speed during the whole journey in $\text{km/h}$?

$A$ person sets out to cover a distance of $12 \, km$ in $45 \, minutes$. If he covers $\frac{3}{4}$ of the distance in $\frac{2}{3}$ of the time,what should be his speed to cover the remaining distance in the remaining time? (in $km/h$)

Without any stoppage, a person travels a certain distance at an average speed of $42 \, km/h$ and with stoppages he covers the same distance at an average speed of $28 \, km/h$. How many minutes per hour does he stop?

$A$ car travels the first $39 \, km$ distance in $45 \, minutes$ and the next $25 \, km$ distance in $35 \, minutes$. What is its average speed in $km/h$?