If $$ {x^4}+{1\over{x^4}}$$ then find $$ {x^3}-{1\over{x^3}}=?$$

An office opens at 10 am and closes at 5 pm. The lunch break is of 30 minutes. What is the ratio of lunch break and total office hours?

What is the compound interest on Rs. 48,000 for 2 years at 20% p.a., if interest is compounded annually?

Five years ago, the average age of 4 girls was 7 years. On joining a new girl, the present average age becomes 13 years. The current age of the new girl is:

If x – y + z = 15, xyz = -216 and xz – xy – yz = 18, then the value of $$ {x^3}-{y^3}+{z^3}=$$

Study the following graph carefully to answer the given questions

A is twice efficient as B and together they do the same work in as much time as T and V together. In how many days A can complete the work individually?

The following penalty diagram shows the 4 year exam results of the students of 10th standard. Study the diagram and answer the following questions.

Name the number of students who appeared in the 10th standard examination in the year 2002-

X and Y are centres of circles of radius 9 cm. and 2 cm respectively XY=17 cm. Z is the centre of a circle of radius r cm which touches the above circles externally. Given that - ∠xzy = 90^o the value of r is -