Quantitative Aptitude - Arithmetic Ability Questions

In the following question, four number pairs are given. The number on left side of (–) is related to the number on the right side of (–) with some Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.

If a3+1a3 = 2, then the value of a2+1a?

If tanθ = 815, then 1-sinθ1+sinθ is

The sum of a non-zero number and its reciprocal is 2. What is the number?

In the following question, select the odd letter/letters from the given alternatives.

The ratio of two numbers is 6 : 11 and their difference is 65. What will be the smaller number among both the numbers?

If sinC + sinD =X, then the value of X is?

Two numbers are 10% and 20% lesser than a third number respectively. By how much percent is the second number should be enhanced to make it equal to the first number?