Quantitative Aptitude - Arithmetic Ability Questions

The average of 5 members of a family is 24 years. If the youngest member is 8 years old, then what was the average age (in years) of the family at the time of the birth of the youngest member?

The mean of 10 observations is 17. One more observation is included and the new mean becomes 16. The 11th observation is

A money lender lends Rs. 400 for 3 years to a person and lends Rs. 500 for 4 years to the other person at the same rate of simple interest. If altogether he receives Rs. 160 as interest, what is the rate of interest per annum ?

Select the odd letters from the given alternatives.

Find the sum of interior angles of a dodecagon?

What is the third proportional to 9 and 15?

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 2 - 2z + z22 + 2z - z2, when z+2z = 2 ?