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Exercise

Question 5

You can compute the ratio of the number of boys divided by the number of girls born in 1940 manually by typing 1211684/1148715.

You can get that same ratio for all years by typing 

present$boys/present$girls

Similarly, you can calculate the proportion of male newborns in 1940 by typing 

1211684/(1211684 + 1148715)

To get that proportion for all years use present$boys/(present$boys + present$girls).

Note that with R as with your calculator, you need to be conscious of the order of operations. Here, we want to divide the number of boys by the total number of newborns, so we have to use parentheses. Without them, R will first do the division, then the addition, giving you something that is not a proportion.

Make a plot of the proportion of boys over time, and based on the plot determine if the following statement is true or false: The proportion of boys born in the US has decreased over time.

Tip: In the console, if you use the up and down arrow keys, you can scroll through your previous commands, your so-called command history. This will save you a lot of typing in the future.

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50 XP
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