City Guilds Model Questions Vol1 2018 Engineering Question 42
Practice objective / multiple choice question 42 from the 2018 City Guilds Model Questions Vol1 Engineering examination.
In a workshop two solvents, A and B, have permissible exposure limits (PEL) of 50 ppm and 30 ppm respectively. When both are present the combined exposure is assessed by \(\frac{C_A}{PEL_A}+\frac{C_B}{PEL_B}\le 1\). Over a 2‑hour task the concentrations change uniformly from \(C_A=20\) ppm, \(C_B=10\) ppm at the start to \(C_A=45\) ppm, \(C_B=25\) ppm at the end. How many minutes within the 2‑hour period does the combined exposure exceed the safe limit?
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About This Question
This is City Guilds Model Questions Vol1 2018 Engineering Question 42. It is one of the objective questions from the 2018 City Guilds Model Questions Vol1 Engineering examination.
Difficulty level: Medium .
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