Answer:
2.28% of babies born in the United States having a low birth weight.
Step-by-step explanation:
<u>The complete question is</u>: In the United States, birth weights of newborn babies are approximately normally distributed with a mean of μ = 3,500 g and a standard deviation of σ = 500 g. What percent of babies born in the United States are classified as having a low birth weight (< 2,500 g)? Explain how you got your answer.
We are given that in the United States, birth weights of newborn babies are approximately normally distributed with a mean of μ = 3,500 g and a standard deviation of σ = 500 g.
Let X = <u><em>birth weights of newborn babies</em></u>
The z-score probability distribution for the normal distribution is given by;
                           Z  =   ~ N(0,1)
  ~ N(0,1)
where,  = population mean = 3,500 g
 = population mean = 3,500 g
              = standard deviation = 500 g
 = standard deviation = 500 g
So, X ~ N( )
)
Now, the percent of babies born in the United States having a low birth weight is given by = P(X < 2500 mg)
          
    P(X < 2500 mg) = P(  <
 <  ) = P(Z < -2) = 1 - P(Z
 ) = P(Z < -2) = 1 - P(Z  2)
 2)
                                                                  = 1 - 0.97725 = 0.02275 or 2.28%
The above probability is calculated by looking at the value of x = 2 in the z table which has an area of 0.97725.