3. Marks of a student were wrongly entered in computer as 83, actual marks of that student were 63. Due to this mistake average marks of whole class got increased by half (1/2). Find the total number of students in that class.
25
30
35
40
45
Answer: Option D
Explanation:
Suppose total number of students are = X \begin{aligned} Total increase = x*\frac{1}{2} = \frac{x}{2} \\ => \frac{x}{2} = 83-63 = 20 \\ => x = 40 \end{aligned}
4. The average age of the mother and her six children is 12 years which is reduced by 5 years if the age of the mother is excluded. How old is the mother
40
41
42
43
Answer: Option C
5. Average of first five multiples of 3 is
9
11
13
15
Answer: Option A
Explanation:
\begin{aligned}
Average = \frac{3(1+2+3+4+5)}{5} = \frac{45}{5} = 9
\end{aligned}