Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the missing number from the given series.1 108, 81, 54, 27, ?

What is the average of all the one digit, two digit and three digit natural numbers?

There are a total of 200 students in a school, of which 7/10th are boys. Find the number of girls in the school.

What is that least digit that must be added to the product 5786 × 5784 to make it a perfect square?

$$\begin{gathered} If (x – 2)2 + (y + 3)2 + (z – 15)2 = 0, then what is the value of \\ x + y + z – 5? \end{gathered}$$

If 3 dozen guavas cost Rs. 90, how many guavas can be bought for Rs. 240?

Find out the odd word/letters/number/number pair from the given alternatives.