CHST Study Guide Correct Questions & Solutions

If angle A is 63.4 deg, What is the length of side C? Tangent side of angle A is 5, and adjacent side is 10. - ANSWER Sin A = a/c, Sin 63.4=10/c, c=10/sin 63.4=11.2 What is the angle of the ramp that rises 4 feet in a 10 feet run? - ANSWER Tan A = a/b, Tan A = 4/10, A = Arc Tan [4/10], A = 21.801 Based on the allowable limits in the table below if the noise in a work area was 95 dBA for 3 hours, 90 dBA for 5 hours and 85 dBA for 2 hours, is the allowable limited exceeded? - ANSWER C = Time exposed and T = Allowable time exposed C1/T1 + C2/T2 + C3/T3 + Cn/Tn Anything > 1 is exposure not allowed 3/4+5/8+2/no limit = 1.375 > 1 If a vessel contains 70% air and 30% hydrocarbons what is the oxygen content of the vessel? - ANSWER Normal air contains 21% oxygen by volume. The vessel only contains 70% normal air. Therefore 0.7x.21 = 0.147 or 14.7% Compute the TWA concentration from the following measurement data: hrs. @ 100 ppm; hrs. @ 200 ppm; hrs hrs. @ 0 ppm; and hrs. @ 100 ppm. - ANSWER C = PPM exposed to and T = Time exposed to Sum of (C1xT1) + (C2xT2) + (C3xT3) + (C4xT4) divided by the Sum of T1 + T2 + T3 + T4 300+400+0+200=900 / 3+2+1+2=8 = 112.5 If a job site operation results in a $45,000 loss every 3 years, what is the expected loss over a period of years? - ANSWER Solve for yearly loss, 45,000/3 = 15,000 Multiply by 12, 15,000x3 = 180,000 A radioisotope has a half-life of 1 year. How many years will it take to reduce the initial activity to less than 10%. - ANSWER 4 years 100% 1 year = 50%, 2 Years = 25%, 3 years = 12.5, 4 years = 6.25% How much does a 55 gallon drum of acid weigh, if the specific gravity of the acid is 2.1. Note water weighs 8.34 lbs per gallon? - ANSWER Specific gravity (SG) is the ratio of a substance compared to an equal volume of water. In this case one gallonof acid weighs 2.1 time the weight of water. The Formula then becomes # of gallons x 8.34 x SG. 55X8.34x2.1 = 963.3 lbs A 1200 lbs load is lifted with a 2 leg sling whose legs are at 30 Deg angel with the load. The stress on each leg is? - ANSWER Sin A = a/c, c=a/sin A, c=600/sin 30, c=1200 lbs A 20,000 lbs load is lifted with a 2 leg sling whose leg