The average speed of a train running at a speed of $30\, km / h$ during the first $100\, kilometres,$ at $40\, km / h$ during the second $100\, kilometres$ and at $50\,km / h$ during the last $100\, kilometres$ is nearly (in $km/h$)
$38.5$
$38.3$
$40.0$
$39.2$
$A , B , C , D\, \& \,E$ are five consecutive even numbers. Average of $A$ and $E$ is $46 .$ What is the largest number?
A motorist covered the first $20\, km$ of his journey in 30 mifitutes and the remaining $29\, km$ in $40\, minutes$. His average speed in $km / hr$ is:
The average of $5$ quantities is $6 .$ The average of three of them is $8 .$ What is the average of remaining two quantities?
The average of the first $7$ integers in series of $13$ consecutive odd integers is $37 .$ What is the average of the entire series ?
The average of marks obtained by $100$ candidates in a certain examination is $30 .$ If the average marks of passed candidates is $35$ and that of the failed candidates is $10,$ what is the number of candidates who passed the examination?