A bakery producing chocolate muffins wants to advertise the size of their muffins on the packaging. Over the next 25 trays of muffins produced, they select the middle muffin and measure its diameter. The average diameter of the 25 muffins selected is 5.6cm with standard deviation of 2.1cm. a. [5 marks] Construct a 95% confidence interval mean diameter of the muffins. Show formulas used in calculations. Explain what confidence multiplier you used and why. b. [4 marks] Give an example of a potential source of bias this sampling scheme may suffer from. Explain how you could modify the sampling scheme to avoid this source of bias