The average speed of a train in the onward journey is $25\, \%$ less than that of the return journey, The train halts for one hour on reaching the destination. The total time taken for the complete to and fro journey is $17\, hours,$ covering a distance of $800 \,km$. The speed of the train in the onward journey is (in $km/h$)

The average weight of $8$ sailors in a boat is increased by $1\, kg$ if one of them weighting $56\,kg$ is replaced by a new sailor. The weight of the new sailor is (in $kg$)

Ashish has earned an average of $4200$ dollars for the first eleven months of the year. If he justifies his staying on in the US on the basis of his ability to earn at least $5000$ dollars per $month$ for the entire $year,$ how much should heearn (in $dollars$) in the last $month$ to achieve his required average for the whole $year$ ?

The average revenue of $13$ consecutive years of a company $Rs.\, 70$ $\,lakhs.$ If the average of first $7 \,years$ is $Rs.\, 65$ $\,lakhs$ and that of last $7\, years$ is $Rs.\, 77$ $\,akhs,$ find the revenue for the $7^{th}$ $year.$ (Rs. in $lakh$)

$10\, kg$ of rice priced at $Rs. \,12$ per $kg$ is mixed with $6\, kg$ of rice priced at $Rs. \,16$ per $kg$. Find the average price in $Rs.$ per $kg$ of the whole mixture?