Answer:
(A) 342 ppm
(B) 325 ppm
Explanation:
We assume that 5% of the current level is being removed in the month.
(A)
After 1 month, the pollution level is multiplied by 1-5% = 0.95:
0.95 × 360 ppm = 342 ppm
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(B)
After another month, the pollution level is again multiplied by 0.95:
0.95 × 342 ppm ≈ 325 ppm