Having issues plotting Gaussian curve on histogram? (Used previous examples and no luck)

Question

First off, here is the code:

hist(sumCol)
curve(dnorm(sumCol, mean=Mean, sd=SD), 
      col="darkblue", lwd=2, add=TRUE, yaxt="n")

I used the code I found here but no luck. Any help would be much appreciated. The mean is 49.9 and SD is 6.66.

> dput(sumCol)
c(47.4105366033036, 58.3324683033861, 58.1094471025281, 49.9950564198662, 
46.136499152286, 57.6314454714302, 55.9323056084104, 42.4964612387121, 
56.1618362078443, 42.376149847405, 56.1894942307845, 50.9596610828303, 
44.9340054308996, 56.2675485799555, 44.5740411255974, 55.4805521473754, 
50.7398278019391, 48.7541372219566, 36.393867429113, 46.3503022803925, 
55.629230362596, 41.7389209344983, 37.9173863746691, 49.6265010556672, 
52.5780587899499, 48.2867740916554, 47.6546685318463, 55.3406274791341, 
42.1973585763481, 44.8090796419419, 45.2378696959931, 49.4975818633102, 
49.5211400222033, 66.1860005331691, 64.2629869871307, 52.9526992985047, 
43.8075632608961, 52.2976646479219, 49.4498609972652, 43.0183454982471
)

Answer 1

The easy thing to get is the histogram with the curve when the height is the probability density.

hist(sumCol, prob=TRUE)
sumCol_norm = function(x) { dnorm(x, mean=mean(sumCol), sd=sd(sumCol)) }
curve(sumCol_norm,  col="darkblue", lwd=2, add=TRUE, yaxt="n")

This gives exactly the shape that you want but the y-axis labels are the density, not the counts. In order to do this with the counts as in your original histogram, we need to scale the density by the total count of all the bins. We can get that by saving the output of the histogram and making a minor computation.

H = hist(sumCol)
area = sum(diff(H$breaks)*H$counts)
sumCol_norm = function(x) { area*dnorm(x, mean=mean(sumCol), sd=sd(sumCol)) }
curve(sumCol_norm,  col="darkblue", lwd=2, add=TRUE, yaxt="n")