According to U.S. Inspect, roofing shingles weighed approximately 240 pounds per square foot prior to 1973, and modern shingles weigh approximately 190 pounds per square foot, depending on the...

According to U.S. Inspect, roofing shingles weighed approximately 240 pounds per square foot prior to 1973, and modern shingles weigh approximately 190 pounds per square foot, depending on the material and the manufacturer. Suppose a brand of recycled synthetic shingles is advertised to weigh 185 pounds per square foot. A random sample of these shingles was obtained, and the weight of each is given in the following table.