The average weight of $45$ students in a class was calculated as $36 \,kg$. It was later found that the weight of two students in the class was wrongly calculated. The actual weight of one of the boys in the class was $32 \,kg ,$ but it was calculated as $34$ $kg ,$ and the weight of another boy in the class was $45 \,kg ,$ whereas it was calculated as $40 \,kg$. What is the actual average weight of the $45$ students in the class ? (in $kg$) (Rounded off to two-digits after decimal) 

The average weight of a class of $24$ students is $35 \,kg$. If the weight of the teacher is included the average rises by $400\, g.$ The weight of the teacher is (in $kg$)

If the mean of $a, b, c$ is $M$ and $a b+b c+c a=0,$ then the mean of $a^{2}, b^{2}, c^{2}$ is

Find average of all prime numbers between $60$ and $90.$

Out of $9$ persons$, 8$ persons spent $Rs.\, 30$ each for their meals. The nineth one spent $Rs.\, 20$ more then the average expenditure of all the nine. The total money spent by all of them was (in $Rs.$)

The average salary of workers in $AMS$ careers is $Rs.\, 2,000$ , the average salary of faculty being $Rs. \,4,000$ and the management trainees being $Rs. \,$ $1,250 .$ The total number of workers could be