Problems 279
Annual Floods of the Blackstone River (1929–1965)
Flood Discharge
Year (ft^3 /s)
1929 4,570
1930 1,970
1931 8,220
1932 4,530
1933 5,780
1934 6,560
1935 7,500
1936 15,000
1937 6,340
1938 15,100
1939 3,840
1940 5,860
1941 4,480
1942 5,330
1943 5,310
1944 3,830
1945 3,410
1946 3,830
1947 3,150
1948 5,810
1949 2,030
1950 3,620
1951 4,920
1952 4,090
1953 5,570
1954 9,400
1955 32,900
1956 8,710
1957 3,850
1958 4,970
1959 5,398
1960 4,780
1961 4,020
1962 5,790
1963 4,510
1964 5,520
1965 5,300- A manufacturer of heat exchangers requires that the plate spacings of its exchang-
ers be between .240 and .260 inches. A quality control engineer sampled 20
exchangers and measured the spacing of the plates on each exchanger. If the
sample mean and sample standard deviation of these 20 measurements are .254