Question

1. the following is a boxplot of the birth weights (in ounces) of a sample of 160 infants born in a local hospital. boxplot image birth weight (ounces) 80 90 100 110 120 130 140 about 40 of the birth weights were below (a) 92 ounces. (b) 102 ounces. (c) 112 ounces. (d) 122 ounces. (e) 132 ounces.

Explanation:

Step1: Recall boxplot quartiles

A boxplot divides data into four quartiles, each representing 25% (or $\frac{1}{4}$) of the data. For a sample of 160 infants, each quartile has $160\times\frac{1}{4} = 40$ data points. The first quartile ($Q_1$) is the value where 25% (40 data points) of the data is below it.

Step2: Analyze the boxplot

In a boxplot, the left edge of the box represents the first quartile ($Q_1$). Looking at the boxplot, the left edge of the box is around 102 ounces (visually, between 100 and 110, closer to 100 - 102 range). So 25% (40) of the data is below $Q_1$, which is around 102 ounces.

Answer:

B. 102 ounces