10.24 The sunspot cycle. Some plots against time show cycles of up-and-down movements. Figure 10.19 is a line graph of the average number of sunspots on the sun's visible face for each month from 1900 to 2011. What is the approximate length of the sunspot cycle? That is, how many years are there between the successive valleys in the graph? Is there any overall trend in the number of sunspots? 250 - 200 150 Average number of sunspots 100 50 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Moore/Notz, Statistics: Concepts and Controversies, 10e, @ 2020 W. H. Freeman and Company Figure 10.19 The sunspot cycle, Exercise 10.24. This is a line graph of the average number of sunspots per month for the years 1900-2011. Data from the National Oceanic and Atmospheric Administration