The average weight of a group of $20$ boys was calculated to be $89.4 kg$ and it was later discovered that one weight was misread as $78 kg$ instead of the correct one of $87 kg$. The correct average weight is in $kg$
$88.95$
$89.25$
$89.55$
$89.85$
The average marks of students in an examination was $65 .$ It was later found that the marks of one students had been wrongly entered as $83$ instead of $38.$ the correct average is ?
The average age of a group of persons going for a picnic is $16.75 \,years.$ $20$ new persons with an average age of $13.25 \,years$ join the group on the spot due to which the average of the group becomes $15\, years.$ Find the number of persons initially going for the picnic $?$
Average rainfall on Monday, Tuesday, Wednesday and Thursday is $420.5\, cm$ and average on Tuesday, Wednesday, Thursday and Friday is $440.5\, cm .$ If the ratio of rainfall for Monday and Friday is $20: 21,$ find the rainfall in $cm$ on Monday and Friday.
With an average speed of $40\, km / h ,$ a train reaches its destination on time. If it goes with an average speed of $35 \,Km / h ,$ it reaches late by $15$ minutes. The total journey is (in $km$)
The sum of five numbers is $260 .$ The average of the first two numbers is $30$ and the average of the last two numbers is $70 .$ What is the third number ?