# Industrial Engineering Questions and Answers – Work Sampling

This set of Industrial Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Work Sampling”.

1. Which of the following is related to work sampling?
a) Work simplification
b) Work measurement
c) Motion study
d) Method study

Explanation: Work sampling is one of the work measurement techniques where a large number of observations are made over a period for activities of longer duration. Work measurement is also known as time study. Work simplification is the other name of motion study or method study.

2. Which of the following is the other name of work sampling?
a) Activity sampling
b) PMTS
c) Analytical estimation
d) Synthesis

Explanation: Work sampling is also known as Activity sampling. It is also called as a ratio-delay study. In this technique, a large number of observations are made over a period. It is mainly used for long-duration activities.

3. Who developed the work sampling technique?
a) L H C Tippet
b) R L Marrow
c) C L Brisley
d) Taylor

Explanation: L H C Tippet developed activity sampling in the year 1934 in Britain for the Britain cotton industry research board. It is a statistical-based technique. After a couple of years, this technique became popular and nowadays it is the most commonly used technique.

4. Who named the activity sampling as a ratio-delay study?
a) L H C Tippet
b) R L Marrow
c) C L Brisley
d) Taylor

Explanation: Even though activity sampling is developed by L H C Tippet, R L Marrow named used this technique around 1945 in America. He named this technique as a ratio-delay study.

5. Who was the one that named activity sampling as work sampling?
a) L H C Tippet
b) R L Marrow
c) C L Brisley
d) Taylor

Explanation: C L Brisley named activity sampling as work sampling around 1952. An operation or a process or activity of longer durations can be economically timed using this technique.

6. What type of observations are considered in the working sampling technique?
a) Random observations
b) Continuous observations
c) Random observations or continuous observations
d) Random observations and continuous observations

Explanation: Work sampling uses random observations taken at different times in a day or over a period. More the number of observations, more the accuracy of time.

7. Which of the following work measurement technique uses the statistical theory of sampling and probability theory?
a) Work sampling
b) Stopwatch method
c) Synthesis
d) Analytical estimating

Explanation: Work sampling is a work measurement technique that uses the statistical theory of sampling and probability theory. Work sampling also relies on normal frequency distribution and confidence level.

8. How much time of a stopwatch time study method is required for a work sampling technique?
a) $$\frac {1}{20}$$
b) $$\frac {1}{200}$$
c) $$\frac {1}{120}$$
d) $$\frac {1}{2}$$

Explanation: Work sampling is used for longer duration activities and irregular work cycles whereas stopwatch time study is suitable for shorter cycle times. Work sampling requires only ($$\frac {1}{20}$$)th time of a stopwatch time study method.

9. Which of the following equation is used to calculate the number of observations(N) required in work sampling?
a) $$\frac {4P(1-P)}{L \times L}$$
b) $$\frac {4P(1-P)}{L+ L}$$
c) $$\frac {4P(1+P)}{L \times L}$$
d) $$\frac {4P(1+P)}{L+ L}$$

Explanation: Let, L be the limits of error
N = sample size
S = Desired accuracy level
P = Percentage occurrence of activity or delay
Then, S \times P = L = K$$\sqrt {\frac {P(1-P)}{N}}$$
For a 95% confidence level, K = 2
L = 2$$\sqrt {\frac {P(1-P)}{N}}$$
L2 = $$\frac {4P(1-P)}{N}$$
∴ $$\frac {4P(1-P)}{L \times L}$$

10. Find the number of observations required for 95% confidence level and at an accuracy of ±2% when the percentage of occurrence of activity is 60%?
a) 2400
b) 2404
c) 2440
d) 2024

Explanation: Given, P = 60% = 0.6
K = 95% confidence level = 2
L = ±2%
N = $$\frac {4P(1-P)}{L \times L} = \frac {4 \times 0.6(1-0.6)}{0.02 \times 0.02}$$ = 2400

Sanfoundry Global Education & Learning Series – Industrial Engineering.

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