1. Practice Problems: Supplement 10 (S10), Work Measurement
Problem 1:
Carolyn Barrett, a marketing surveyor, takes an average of 10 minutes to complete a
particular questionnaire. Carolyn’s performance rating (pace) is 110% and there is an
allowance of 15%.
What is the Normal time for completing this questionnaire?
What is the Standard time for completing this questionnaire?
Problem 2:
Tom Leonard, of Leonard, Spitz, and Wareham, takes 3 hours and 25 minutes to write
an end of month report. Tom is rated at 95% (work pace is 95%) and the office has a
personal time allowance of 8%. There is no delay time or fatigue time.
What is the Normal time for writing an end of month report?
What is the Standard time for writing an end of month report?
Problem 3:
The two steps in preparing chocolate candy bars are molding and packaging. Personal
fatigue and delay allowances are set at 15%. The molding machine operator is rated at
110% and the packer is rated at 80%. Observed times per batch are given below.
Observed Time in Minutes
Task
1
2
3
4
Molding
26
30
29
31
Packing
45
50
35
30
Determine the Normal and standard times for both tasks.
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2. Problem 4:
A work-study sample of a manufacturing activity conducted over a 40-hour period
shows that a worker with an 85% rating produced 12 parts. The worker’s idle time
was 10% and the allowance factor was 12%
Find the Normal and Standard time for this activity.
Problem 5:
Jim and Bob recently time-studied a janitorial task. From a sample of 75 observations,
they computed an average cycle time of 15 minutes with a standard deviation of 2
minutes. Was their sample large enough that one can be 99% confident that the
standard time is within 5% of the true value?
Problem 6:
Consider the following task broken down into 5 MTM elements:
TMUs
Code in MTM Books
Reach to tool box
14.2
R12D
Grasp a tool
3.5
BG1
Separate tool by pressing
10.6
AP2
Turn tool
3.5
T45S
Move and focus eyes
13.4
M12B
What is the total time for the task?
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3. ANSWERS
Problem 1:
Normal time = (total time)(%working on this task)(rating)/(number of units produced)
= (10)(1.00)(1.10)/1 = 11 minutes
Standard time =
Total Normal time
11
11
=
=
= 12.9 minutes
1-Allowance factor 1 − 0.15 .85
Problem 2:
Normal time = (total time)(%working on this task)(rating)/(number of units produced)
= (205 minutes)(1.00)(0.95)/1 = 194.75 minutes
Standard time =
Total Normal time 194.75 194.75
=
=
= 211.68 minutes
1-Allowance factor 1 − 0.08
.92
Problem 3:
Observed Times in Minutes
Task
1
2
3
4
Molding
26
30
29
31
Packing
45
50
35
30
For Molding:
Average for the actual Molding cycle = 29 minutes per batch
Normal time = (total time)(% working)(rating)/(number of units produced)
= (29)(1.00)(1.10) /1 = 31.9 minutes per batch
Standard time = (Normal time)/(1-Allowance)
= 31.90 /(1 − 0.15) = 37.5 minutes per batch
For Packing:
Average actual Packing time = 40 minutes
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4. Normal time = (total time)(%working)(rating)/(number of units produced)
= (40)(1.00)(.80) = 32 minutes per batch
Standard time = (Normal time)/(1-Allowance)
= (32)/(1 − 0.15) = 37.6 minutes
Problem 4:
Average actual time = 40 hours
Normal time = (total time)(%working)(rating)/(number of units produced)
= (40hrs)(0.90)(0.85)/(12) = 2.55 hours per part
Standard time = (Normal time)/(1-Allowance)
= 2.55 / 0.88 = 2.90 hours per part
Problem 5:
To find the number of samples required:
2
 zσ 
n=
÷ where h is the accuracy desired and z is the confidence level
h−x 
2
2
 2.575* 2   5.15 
n=
÷ =
÷ = 47.15 or 48 samples
 0.05*15   .75 
Therefore, the sample size of 75 is sufficient.
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5. Problem 6:
TMUs
Reach to tool box
Code in MTM Books
14.2
R12D
3.5
BG1
10.6
AP2
3.5
T45S
Move and focus eyes
13.4
M12B
TOTAL
45.2
Grasp a tool
Separate tool by pressing
Turn tool
Remember: 1 TMU = .0006 minutes.
Translating to minutes: 45.2 TMUs * .0006 = .027 minutes
Translating to seconds: .027 minutes * 60 = 1.627 seconds
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6. Problem 6:
TMUs
Reach to tool box
Code in MTM Books
14.2
R12D
3.5
BG1
10.6
AP2
3.5
T45S
Move and focus eyes
13.4
M12B
TOTAL
45.2
Grasp a tool
Separate tool by pressing
Turn tool
Remember: 1 TMU = .0006 minutes.
Translating to minutes: 45.2 TMUs * .0006 = .027 minutes
Translating to seconds: .027 minutes * 60 = 1.627 seconds
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