Exercise

# Calculating confidence intervals

Now you will calculate the confidence intervals for the A/B test results.

The four values that have been calculated previously have been loaded for you (`cont_conv`

, `test_conv`

, `test_size`

, `cont_size`

) as variables with those names.

Instructions

**100 XP**

- Calculate the mean of the distribution of our lift by subtracting
`cont_conv`

from`test_conv`

. - Calculate the variance of our lift distribution by completing the calculation. You must complete the control portion of the variance.
- Find the standard deviation of our lift distribution by taking the square root of the
`lift_variance`

- Find the confidence bounds for our A/B test with a value equal to our
`lift_mean`

, a 0.95 confidence level, and our calculated`lift_sd`

. Pass the arguments in that order.