The SAT mathematics scores in the state of Florida are approximately normally distributed with a mean of 500 and a standard deviation of 100.Using the empirical rule, what is the probability that a randomly selected student’s math score is between 300 and 700? Express your answer as a decimal.
Question
Answer:
0.9544 is the probability that a randomly selected student’s math score is between 300 and 700 .Step-by-step explanation:Step 1: Sketch the curve.
The probability that 300<X<700 is equal to the blue area under the curve.Step 2:
Since μ=500 and σ=100 we have:
P ( 300<X<700 )=P ( 300−500< X−μ<700−500 )⇒P ( 300−500/100 < X−μ/σ < 700−500/ 100)
Since Z = x − μ /σ , 300−500 /100 = −2 and 700−500/100 = 2 we have:
P ( 300<X<700 )=P ( −2<Z<2 )
Step 3: Use the standard normal table to conclude that:
P ( −2<Z<2 )=0.9544Therefore,0.9544 is the probability that a randomly selected student’s math score is between 300 and 700 .
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