What proportion of trucks can be expected to travel between 34 and 50 thousand miles in a year?
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What proportion of trucks can be expected to travelbetween 34 and 50 thousand miles in a year?b. What percentage of trucks can be expected to traveleither below 30 or above 60 thousand miles in a year?c. How many miles will be traveled by at least 80% of thetrucks?d. What are your answers to (a) through (c) if the standarddeviation is 10 thousand miles?Mean50,000 milesStd. Dev12,000 milesFrom 34 to 50z=(X-mean)/sZ value for 34-1.330.0918Z value for 50a.00.5000P(– 1.33 < Z < 0)0.4082b.P(X < 30)Z value for 30-1.670.0475P(X > 60)Z value for 600.830.79670.2033P(Z < – 1.67) + P(Z > 0.83)0.2508P(X > A) = 0.80c.P(Z < – 0.84)2 Std. DevZ= -.84-1008039,920 Milesd.If Std Dev changes to 10,000 miles the Z value will increaseFrom 34 to 50Z value for 34-1.600.0548Z value for 5000.5000P(– 1.60 < Z < 0)0.4452P(X < 30)Z value for 30-2.000.0228P(X > 60)Z value for 601.000.84130.1587P(Z < – 1.67) + P(Z > 0.83)0.1815P(X > A) = 0.80P(Z < – 0.84)2 Std. Dev