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.

What is the value of Tan 45° - 1/√3 Sec 60°?

A balloon leaves from a point P rises at a uniform speed. After 6 minutes, an observer situated at a distance of 450√3 metres from point P observes that angle of elevation of the balloon is 60 deg. Assume that point of observation and point P are on the same level. What is the speed (in m/s) of the balloon?

Diameter of wheel of a cycle is 21 cm. The cyclist takes 45 minutes to reach a destination at a speed of 16.5 km/hr. How many revolutions will the wheel make during the journey?

Rathin is now 16 years old while his cousin is 7 years. After how many years will Ratin's age be 1.5 times that of his cousin?

What is the mean of the first five Triangular Numbers?

If 192 pens cost is Rs.10, how many pens can be bought for Rs.5?

Karteek is twice as good a foreman as Raju and together they finish a piece of work in 20 days. In how many days will Raju alone finish the work?