A traffic study of 2,500 vehicles that passed by a checkpoint showed that their speeds were normally distributed with a mean of 82.5 kph and a standard deviation of 11.5 kph. How many vehicles had a speed of more than 90 kph?
"\\mu=82.5 \\\\\n\n\\sigma= 11.5 \\\\\n\nP(X>90) = 1 -P(X<90) \\\\\n\n= 1 -P(Z< \\frac{90-82.5}{11.5}) \\\\\n\n= 1 -P(Z< 0.652) \\\\\n\n= 1 -0.7428 \\\\\n\n= 0.2572 \\\\\n\nN = 2500 \\times 0.2572 = 643"
Answer: 643
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