Suppose the amount (in HK Dollars) spent on lunch of a random sample of 200 people on a certain day is summarized in the grouped frequency distribution below. Amount spent on lunch (HKD) Frequency 20 -39 20 40 - 59 54 60 -79 80 80 99 36 100 - 119 10 (i) Find the sample mean of the above grouped frequency distribution. (ii) Find the sample variance of the above grouped frequency distribution. Mr. Chan spent $90 on lunch that day. Find the standard score of this amount and interpret the meaning of the standard score. Correct your answer to 2 decimal places