import pandas as pd
import numpy as np
#from scipy.stats import norm
from scipy.stats import t

data1 = pd.read_excel("http://kanggc.iptime.org/book/data/chap10-2-1.xlsx")
data1

var1 = data1['var1']
var1.describe()

print("Data Frame of data1 is : ",f'\n{data1}\n')
print("Summary Statistics of data1 is : ", f'\n{data1.describe()}\n')

n = len(var1)
s = np.std(var1, ddof=1)

xbar = np.mean(var1)
t19 = t.ppf(0.975, 19)

lcl1 = xbar - t19*(s/np.sqrt(n))
ucl1 = xbar + t19*(s/np.sqrt(n))

print("The t value is :", t19)
print("The Lower Confidence Limit is :", lcl1)
print("The Upper Confidence Limit is :", ucl1)