Plant Operator Selection System Test Plant Operator Selection System Tables and Graphs Interpretation 3

Question 1

An equipment maintenance log shows the following hours between failures for a compressor: 820, 950, 780, 1100, 870. What is the median time between failures?

Accepted Answer

870 hours

Answer

Arranged in order: 780, 820, 870, 950, 1100 — the middle value (median) is 870 hours.

Question 2

A control chart shows that acceptable pH levels range from 6.8 to 7.2. Hourly readings are: 7.0, 7.1, 7.3, 6.9, 7.0. Which reading is out of specification?

Accepted Answer

7.3

Answer

A pH of 7.3 exceeds the upper control limit of 7.2 and falls outside the acceptable range.

Question 3

A graph shows steam pressure in Boiler A and Boiler B over 8 hours. Boiler A averages 120 psi and Boiler B averages 95 psi. What is the ratio of Boiler A's average pressure to Boiler B's?

Accepted Answer

24:19

Answer

120:95 simplifies by dividing both by 5 to give 24:19.

Question 4

A table shows electricity consumption (kWh) by shift: Day=12,400, Evening=10,800, Night=9,600. The plant's daily energy budget is 34,000 kWh. By how much does actual usage differ from the budget?

Accepted Answer

1,200 kWh under budget

Answer

Total usage = 12,400 + 10,800 + 9,600 = 32,800 kWh, which is 34,000 − 32,800 = 1,200 kWh under budget.

Question 5

A scatter plot shows that as ambient temperature increases, cooling water demand also increases. This relationship is best described as:

Accepted Answer

Positive correlation

Answer

When both variables increase together, the scatter plot shows a positive correlation.

Plant Operator Selection System Test Practice Test

Plant Operator Selection System Test Practice Test

Plant Operator Selection System Test Plant Operator Selection System Tables and Graphs Interpretation 3