EXCERSIZE4PT1

x <- sample(x=1:100, size=100, replace=TRUE)
head(x)

## [1] 17 37 77 38 61 25

length(x)

## [1] 100

mean(x)

## [1] 50.71

x[1:25]

##  [1] 17 37 77 38 61 25  4 82 91 60 12 19 19 69 24 40 79 26  2 27 84 29 24 41 43

knitr::opts_chunk$set(echo = TRUE)

x <- sample(x=1:100, size=100, replace=TRUE)
head(x)

## [1]  9  5 96 55 96 27

length(x)

## [1] 100

mean(x)

## [1] 45.89

x[1:25]

##  [1]  9  5 96 55 96 27 29 94 91 17 15  7 71 13 63 16 27 37 21 80 17 10 31 44 24

grades <- c(95, 72, 87, 66)
weights <- c(1/2, 1/4, 1/8, 1/8)
mean(grades)

## [1] 80

sum(weights)

## [1] 1

weighted.mean(x=grades, w=weights)

## [1] 84.625

sum(grades*weights)/4*4

## [1] 84.625

x <- sample(x=1:100, size=100, replace=TRUE)
head(x)

## [1] 65 92 56 89 85 89

length(x)

## [1] 100

mean(x)

## [1] 52.27

x[1:25]

##  [1] 65 92 56 89 85 89 49 57 68 25 37 51  4 24 43  6 58 78 60 86 87 86 41 86 35

y <- x


yy <- sample(x=1:100, size=20, replace=FALSE)
y[yy] <- NA  # Set 20 random elements in y to NA