Subject: General Aptitude · Chapter: Average · Exam: · Marks: · Difficulty:
The following table shows the number of working hours and the number of employees employed in a small scale industry.
No. of working hours
No. of employees
3-5
7
5-7
10
7-9
18
9-11
57
11-13
14
13-15
8
The average number of working hours of an employee is
(a)8.5
(b)9.5
(c)10.5
(d)None of these
Answer
Answer (as printed): B
Explanation
We have: Mean working hours | 4 | 6 | 8 | 10 | 12 | 14 ; No. of employees | 7 | 10 | 18 | 57 | 14 | 8 Sum of working hours of all the employees $$\begin{aligned} & =(4 \times 7+6 \times 10+8 \times 18+10 \times 57+12 \times 14+14 \times 8) \\ & =(28+60+144+570+168+112)=1082 . \end{aligned}$$ Total number of employees $$=(7+10+18+57+14+8)=114 .$$ ∴ Average number of working hours $$=\left(\frac{1082}{114}\right)=9.49 \approx 9.5 .$$
Explanation as extracted from the printed page; notation may be imperfect.