. MafEulli et al. studied the effectiveness of early weightbearing and ankle mobilisation therapies following acute repair of a ruptured Achilles tendon. One of the variables they measured following treatment was the isometric gastrocsoleus muscle strength. In 19 subjects, the mean isometric strength for the operated limb (in newtons) was 259.8 with a standard deviation of 139.9. We assume that these 19 patients constitute a random sample from a population of similar subjects. We wish to use these sample data to estimate for the population the mean isometric strength after surgery. 1. Construct 90% condence interval for the mean isometric strength after surgery. 2. Construct 95% condence interval for the mean isometric strength after surgery. 3. Which one is wider