library(gtools) 
library(knitr)

1.

x <- c(6,7,8,9,10,11,12,13,14)
ninios <- c(37369, 87436, 160840, 239719, 286719, 306533, 310787, 302604, 289168)
n = sum(ninios)

prob.x <- ninios/ n

x
## [1]  6  7  8  9 10 11 12 13 14
prob.x
## [1] 0.01848875 0.04325998 0.07957747 0.11860378 0.14185758 0.15166079 0.15376551
## [8] 0.14971687 0.14306925

2.

v.e <- sum(x * prob.x)
v.e
## [1] 10.99913

3.

prob.acum.x <- c(sum(prob.x[1]), sum(prob.x[1:2]), sum(prob.x[1:3]),
                 sum(prob.x[1:4]), sum(prob.x[1:5]), sum(prob.x[1:6]),
                 sum(prob.x[1:7]), sum(prob.x[1:8]), sum(prob.x[1:9]))
prob.acum.x
## [1] 0.01848875 0.06174874 0.14132621 0.25992999 0.40178757 0.55344837 0.70721387
## [8] 0.85693075 1.00000000

4.

tabla <- data.frame(1:9, x, prob.x, prob.acum.x, x * prob.x, (x - v.e) ^ 2, (x - v.e) ^ 2 * prob.x)

colnames(tabla) <- c("pos","x", "prob.x", "prob.acum.x", "x.prob.x", "x-v.e^2", "x-v.e^2prob.x")

kable(tabla)
pos x prob.x prob.acum.x x.prob.x x-v.e^2 x-v.e^2prob.x
1 6 0.0184888 0.0184888 0.1109325 24.9912583 0.4620571
2 7 0.0432600 0.0617487 0.3028199 15.9930068 0.6918572
3 8 0.0795775 0.1413262 0.6366198 8.9947553 0.7157799
4 9 0.1186038 0.2599300 1.0674340 3.9965038 0.4740005
5 10 0.1418576 0.4017876 1.4185758 0.9982523 0.1416097
6 11 0.1516608 0.5534484 1.6682687 0.0000008 0.0000001
7 12 0.1537655 0.7072139 1.8451861 1.0017493 0.1540345
8 13 0.1497169 0.8569307 1.9463193 4.0034977 0.5993912
9 14 0.1430693 1.0000000 2.0029696 9.0052462 1.2883739

5.

barplot(height = tabla$prob.x, names.arg = tabla$x)

6.

plot(x,prob.acum.x, type = 'b')

7.

var <- sum((x - v.e) ^ 2 * prob.x)
var
## [1] 4.527104

8.

desv.std <- sqrt(var)
desv.std
## [1] 2.127699

Probabilidades

kable(tabla[,1:4])
pos x prob.x prob.acum.x
1 6 0.0184888 0.0184888
2 7 0.0432600 0.0617487
3 8 0.0795775 0.1413262
4 9 0.1186038 0.2599300
5 10 0.1418576 0.4017876
6 11 0.1516608 0.5534484
7 12 0.1537655 0.7072139
8 13 0.1497169 0.8569307
9 14 0.1430693 1.0000000

9.

 i=5

i = min(tabla$x) - 1
i
## [1] 5
 tabla$prob.acum.x[7-i]
## [1] 0.06174874
cat(tabla$prob.acum.x[7-i] * 100,"%")
## 6.174874 %

10.

 1 - tabla$prob.acum.x[8-i]
## [1] 0.8586738

11.

tabla$prob.acum.x[11-i] - tabla$prob.acum.x[8-i]
## [1] 0.4121222