The arithmetie mean of the scores of a group of students in a test was $52 .$ The brightest $20 \%$ of them secured a mean score of $80$ and the dullest $25 \%$ a mean score of $31.$ The mean score of remaining $55 \%$ is

The average temperature for Monday, Tuesday, Wednesday and Thursday was $48^{\circ}$. The average temperature for Tuesday, Wednesday, Thursday and Friday was $52^{\circ} .$ If the temperature on Monday was $42^{\circ} .$ then the temperature on Friday was (in $degrees$)

The average of the first $7$ integers in series of $13$ consecutive odd integers is $37 .$ What is the average of the entire series ?

A student finds the average of ten $2 -$digit numbers. While copying numbers, by mistake, he writes one number with its digits interchaged. As a result his answer is $1.8$ less than the correct answer. The diference of the digits of the number, in which he made mistake, is

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

A number, $x,$ equals $80 \%$ of the average of $5,7,$ $14$ and a number $y$. If the average of $x$ and $y$ is $26$ then value of $y$ is