If an amount doubles automatically in 8 years, then what is the interest rate?

The edges of a cuboid are in the ratio 1 : 2: 3 and its surface area is  88 sq.cm. The volume of the cuboid is:

If sin A=$${6\over 7}$$, then what is the value of sec A?

The cost of a new scooter is Rs 25000, at the end of each year its value becomes 80% of the starting price of that year, what will be the cost of the scooter after 3 years?

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

2, 6, 10, 19, 36, 69, 134

Directions: The following questions are accompanied by three statements (A) or (I), (B) or (II), and (C) or (III). You have to determine which statement(s) is/are sufficient/necessary to answer the questions.

A shopkeeper sold an article and got Rs 300 as profit. Find the profit percentage.
A. Selling price of the article is Rs 1200.
B. He gave 25% discount, which is Rs 400, on the labelled price.
C. Cost price of the article is Rs 900.

If $$ {Acos^{2}θ+Bsin^{2}θ}={sin^{2}θ(sec^{2}θ+1)\over{sec^{2}θ-1}}$$ and cotθ=?

The average weight of 15 students of a class increases by 1.5 kg when a student of 40 kg is replaced by a new student. What is the weight (in kg) of the new student?