EXERCISE 1.

a.What are the dimensions of the present data frame? [1] 63 3 b.What are the column names? [1] “year” “boys” “girls” c1.Display the years included in the data set. (Type present$year as a command and the data will be displayed when the code block is run.) ```{r}[1] 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 [17] 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 [33] 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 [49] 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

``` c2. What years are included in this data set? 1940 to 2002

EXERCISE 2.

  1. Find the total number of births by year. [1] 2360399 2513427 2808996 2936860 2794800 2735456 3288672 3699940 3535068 3559529 [11] 3554149 3750850 3846986 3902120 4017362 4047295 4163090 4254784 4203812 4244796 [21] 4257850 4268326 4167362 4098020 4027490 3760358 3606274 3520959 3501564 3600206 [31] 3731386 3555970 3258411 3136965 3159958 3144198 3167788 3326632 3333279 3494398 [41] 3612258 3629238 3680537 3638933 3669141 3760561 3756547 3809394 3909510 4040958 [51] 4158212 4110907 4065014 4000240 3952767 3899589 3891494 3880894 3941553 3959417 [61] 4058814 4025933 4021726

  2. Plot the total number of births by year with year on the x axis.

  3. What observations do you make based on the plot? Births were increasing steadily until the 1970s, where they dip down, they do not rise again significantly until the 1980s.

EXERCISE 3.

  1. Make a plot that displays the boy-to-girl ratio for every year in the data set.

  2. What do you conclude based on the plot? Each year more boys are born in comparison to the number of girls.

EXERCISE 4.

  1. What was the greatest number of births in the U.S. during the timeframe of the data? 4268326

  2. In what year was the total number of births in the U.S. the greatest? 1961