The average of a non-zero number and its square is $5$ times the number. The number is
$9$
$17$
$29$
$295$
Let the non-zero number be $x$
$\frac{x+x^{2}}{2}=5 x$
$x+x^{2}=10 x$
$x^{2}-9 x=0$
$x-9=0$
$x=9$
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
A person covers $9\, km$ with a speed of $3 \,km / h , 25 \,km$ with a speed of $5\, km / h$ and $30\, km$ with a speed of $10\, km / h$. Find out the average speed of person in $km / h$ ?
The total marks obtained by a student in Physics, Chemistry and Mathematics together is $120$ more than the marks obtained by him in Chemistry. What is the average marks obtained by him in Physics and Mathematics together ?
Three years ago the average age of a family of $5$ members was $27\, years.$ On addition of a child to the family, the present average age of the family is still $27 \,years.$ Find out the present age of the child. (in $years$)
The average of $100$ observations was calculated as $35.$ It was found later, that one of the observations was misread as $83$ instead of $53 .$ The correct average is
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