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Problem 3 Four friends Beth, Samantha, Zarin and Ruby took part in a relay race consisting of two phases. The first phase of the relay race is divided into three equal parts. They aimed to complete their first phase at an average speed of 8 m/s. Beth went first from the starting point and ran at a speed of 7 m/s, followed by Samantha at 7 m/5. a. At what speed did Zarin need to run to maintain their target average speed for the first phase? D Answer in exact fraction, or rounded to at least 4 decimal places m/s 3 b. The second phase of the race consisted of sprinting back to the starting point. What was the average speed of their entire race if Ruby completed the second phase with a speed of 8 m/s? Answer in exact fraction, or rounded to at least 4 decimal places. m/sProblem 2 The grouped frequency table shows the marks obtained in a test by ALL 7X+4 students of a class. Based on the table, answer the following questions Marks 0-5 510 101 5 1520 20-25 25-30 30-35 3540 40-45 4550 Number of students 3 X14 8 8 12 X 12 2X- 11 8 9 a. Find the mean marks obtained by the students in the test. Answer in exact fraction or rounded to at least 4 decimal places b. Calculate the variance ofthe marks obtained by these students. Answer in exact fraction or rounded to at least 4 decimal places