12, Carmen buys 12 roses
I got this by multiplying 4x3=12
Answer:
For this case assuming that the random variable is X

And replacing n = 24 we got:

And we notate the distribution we got: 
Step-by-step explanation:
Previous concepts
The t distribution (Student’s t-distribution) is a "probability distribution that is used to estimate population parameters when the sample size is small (n<30) or when the population variance is unknown".
The shape of the t distribution is determined by its degrees of freedom and when the degrees of freedom increase the t distirbution becomes a normal distribution approximately.
The degrees of freedom represent "the number of independent observations in a set of data. For example if we estimate a mean score from a single sample, the number of independent observations would be equal to the sample size minus one."
Solution to the problem
For this case assuming that the random variable is X

And replacing n = 24 we got:

And we notate the distribution we got: 
Let us convert all figures into decimals so that we can compare them easily.
Monday 0.3
Tuesday 15% = 0.15
Wednesday 1/6 = 0.1666
Thursday 0.2
Friday 1/8 = 0.125
Clearly, I spent the least amount of time on Friday using IT and the time is 0.125 or 1/8.