4. A landfill manager estimates that the weight of the trash on arriving trucks

Question

4. A landfill manager estimates that the weight of the trash on arriving trucks has bell- shaped distribution with mean 45 tons and standard deviation 7 tons. The proportion of trucks whose load exceeds 52 tons is about: (a).16 (b) .025 (c) 84 (d) 34 (e) .68 5. A coin is flipped and a six-sided die is rolled. What is the probability that the coin lands heads and the die shows four or more? (a) 5 (b) 1 (c) 25 (d) .75 (e) none of the above 6. Given that events A and B are independent and that P(A) = 0.7 and P(B) = 0.2, find P(A or B) (a) 14 (b) .9 (c) 5 (d) 76 (e) 1.04 7. Twelve percent (12%) of the population write with their left hands. Six students enter a classroom that has one left-handed desk free. What is the probability that exactly one of the six students writes with his left hand? (a) .38 (b) .50 (c) .72 (d) .12 (e) 88

Explanation / Answer

Solution:-
4. option (a) 0.16
Explanation:-  
P(X > 52) = P(Z > (52 - 45)/7)
= P(Z > 1)
= 0.1587
= 0.16

5. option c) 0.25

Explanation:- 0.5*0.5 = 0.25

6 . option b) 0.9

Explanation:- 0.7+0.2 = 0.9

7. option a) 0.38

Explanation : P(X = 1) = 0.38

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