If a=25, b=15 , c=-10 then find the value of $$ {a^{3}+b^{3}+c^{3}-3abc\over {(a-b)^{2}+(b-c)^{2} +(c-a)^{2}}}$$

A man travel from A to B at 20 km/Hr. and come back from B to A at 30 km/hr. Find the average speed of the whole journey.

Direction: Study the following information to answer the questions.

In hotel B, the ratio of female customers on Tuesday and Friday was 2 : 3. If on Friday, female customers constituted 50% of the number of customers (male + female), then what was the number of customers (male + female) in hotel B on Friday?

Ram has 5 daughters. The average age of these 5 sisters is 28 years. The youngest one is 16 years old. What was the average age of the 4 daughters before the youngest one was born?

Directions: Find the wrong number in the following number series:

The ratio between Males who use their coupon in Pedicure to that of in Spa is 4: 5, while ratio between Females who use their coupon in Haircutting to that of in Spa is 6: 11. Find total number of people who use their coupons in Spa. 

If $${b\over a}=0.7$$ find the value of $${a-b\over a+b}={11\over34}.$$

What will come in the place of question mark (?) in the following question?

  $$?=5\sqrt{ \left(243 \right)^2}$$

In a school, $${3\over 8}$$ of the number of students are girls and the rest are boys. One-third of the number of boys are below 10 years and $${2\over 3}$$ of the number of girls are also below 10 years. If the number of students of age 10 or more years is 260, then the number of boys in the school is: