Hello, could I get help for part (d) with workings please? And if possible, with some explanation too, so i can better understand the workings. I am unsure with the Chi-square concept and am not sure how to approach it. Thank you.

Part (a) to (c) has been solved! but could I check if 0.6827 is the correct answer for (c) please? thank you so much.

Let o and be the pdf and cdf, respectively, of the standard normal variable Z. Let X = 42 - 1. (a) Find P(X 1.61). (10 marks)