A library has an average of $510$ $visitors$ on Sundays and $240$ on other days. The average number of visitors per day in a month of $30 \,days$ beginning with a Sunday is
$250$
$275$
$280$
$285$
Fifteen movie theatres average $600$ customers per theatre per day. If $six$ of the theaters close down but the total theater attendance stays the same, then the average daily attendance per theatre among the remaining theaters is
The average age of a graph of $9$ students is $20\, years.$ When $6$ more students joined the group, the average age falls by $2\, years.$ Then the average age of new students is
The average marks obtained by $150$ students in an examination is $40 .$ If the average marks of passed students is $60$ and that of the failed students is $20,$ what is the number of students who passed the examination ?
The average of the boys in a class is $16\, years$ and that of girls is $15\, years.$ The average age for the whole class is
Five years ago, the average age of $P$ and $Q$ was $15 \,year.$ Now, average age of $P , Q$ and $R$ is $20 \,year.$ What whould be the age of $R$ after $10$ $year$ in $year$ ?