data(ChickWeight)

# Create T | F vector indicating observations with Diet == "3"

index <- ChickWeight$Diet == "3"

# Create vector of "weight" for observations where Diet == "3" and Time == 20

pre <- subset(ChickWeight[index, ], Time == 20, select = weight)$weight

pre

# Create vector of "weight" for observations where Diet == "3" and Time == 21

post <- subset(ChickWeight[index, ], Time == 21, select = weight)$weight

post

# The pre and post values are paired, each pair corresponding to an individual chick.

cbind(pre, post)

Perform a one-sided, paired t-test on the Time == 20 and Time == 21 paired data.

provide t_stat," "p_value," "crit_t" and "lower_ci."

You are to 'manually' implement the test, rather than use t.test(), but you can use t.test() to confirm your work.

our "alternative" hypothesis is weight gain from day 20 to 21, that we are using paired data,

#and that our confidence interval will extend to positive infinity.