confidence-intervals

The textbook has the following solved exercise in chapter 6 After obtaining the 5.23% figure, I would have set it equal to Standard Error * Critical T like described in equation 6.4 of the textbook. Since we are given n = 37, I would have expected the standard deviation to be calculated...

Hello David, Could you please let me know which are the relevant values you plug in the equation q+1.645*se(q) to obtain the 90% confidence intrerval [0.600, 2.690]? Many thanks.