please help me with these questions

Find the standard deviation of the data in the table below that shows the marks of students in Math 20-2 on their last unit exam: Mark Frequency 55 - 59 4 60 - 64 7 65 - 69 6 70 - 74 11 75 - 79 13 80 - 84 4 85- 89 2 Select one: O a. 6.55 O b. 7.99 O c. 8.23 O d. 7.87Environment Canada compiled data on the number of lightning strikes per square kilometre in Saskatchewan and Manitoba towns from 1999 to 2008. 2.03 1.31 0.25 1.03 1.20 0.17 0.99 1.01 0.24 0.94 0.92 0.09 0.86 0.71 0.05 0.81 0.63 0.01 0.80 0.58 0.00 0.72 0.49 0.52 0.43 0.46 0.40 Determine the standard deviation, to two decimal places. Select one: O a. 0.05 O b. 0.45 O c. 0.25 O d. 0.65At the end of a bowling tournament, three friends analyzed their scores. Erinn's mean bowling score is 92 with a standard deviation of 14. Declan's mean bowling score is 130 with a standard deviation of 18. Matt's mean bowling score is 116 with a standard deviation of 22. Who is the more consistent bowler? Select one: O a. Erinn O b. Matt O c. Impossible to tell. O d. DeclanDetermine the z-score for the given value. H = 510, s = 93, x = 412 Select one: O a. 0.95 O b. -0.95 O c. -1.05 O d. 1.05