The lower explosive limit (LEL) of xylene is 1%.

In a room where xylene solution is being sprayed, an engineer uses a calibrate combustible gas meter to determine that the xylene concentration is 10% of the LEL.

What is the concentration of xylene in this room?
1,000 parts per million (ppm)
10,000 parts per million (ppm)
9% great that the LEL of xylene
11% greater than the LEL of xylene

What is the flow rate of air moving through a portable blowers with a velocity of 120 FT/Min (3.048 m/min), through ha pipe of diameter 10 inches (25.4 cm)
0.425 ft3/min (o.0120 m3/min)
7 ft3/min (0.198 m3/min)
54 ft3/min (1.53 m3/min)
9,420 ft3/min (267 m3/min)

An operator is working on a piece of machinery that is producing noise at 105 DBA. The company threshold level is at 85 DBA with 5 DBA exchange rate. The local authority is 90 DBA with 3 DBA exchange rate.
How long can this operator be exposed without any control and still respect both limits?
Less than 5 minutes
15 minutes
30 minutes
1 hour

A company has decided to perform one random safety audit monthly of their 10 crews. The following are near miss points the crews accrued over the last year.
Crew 1 = 55
Crew 2 = 30
Crew 3 = 56
Crew 4 = 40
Crew 5 = 45
Crew 6 = 25
Crew 7 = 28
Crew 8 = 49
Crew 9 = 40
Crew 10 = 32

A crew is considered to be eligible for the safety audit if it accrued near miss points higher than 40
Which is the probability of a crew being selected for a safety audit?