A person travels $\frac{1}{3}$ of his journey by bus at $60\, km / h$ , $\frac{1}{3}$ by scooter at $30\, km / h$ and the rest by walking at $10 \,km / h$. Find his average speed for the whole journey. (in $km/h$)
$30$
$33 \frac{1}{3}$
$20$
$50$
The average age of $24$ boys and their teacher is $15 \,years.$ When the teacher's age is excluded, the average age decreases by $1\, year.$ The age of the teacher is in $years$ ?
The average of $7$ numbers is $5 .$ If the average of first six of these numbers is $4,$ the seventh number is
The mean of $50$ observations was $36 .$ It was found later that an observation $48$ was wrongly taken as $23 .$ The corrected new mean is
The average of the squares of of first ten natural numbers is
The average of five consecutive odd integers is $27 .$ What is the product of the first and the last number?