7. The time taken by a group of 45 students to complete a times tables test in seconds is shown in the table… Number of Time taken (t secs) Students 30 t < 40 5 ≤ 40 t < 50 11 ≤ 50 t < 60 18 ≤ 60 t < 70 6 ≤ 70 t < 80 5 ≤ (a) Write down the modal class interval (1) (b) Calculate an estimate for the mean time taken to complete the test. (3) [4 marks] 8. In a bag there are red counters, white counters and black counters. There are four times as many red counters than white counters and twice as many white counters as black counters. Write down the ratio of red counters to white counters to black counters. [2 marks]
7. The time taken by a group of 45 students to complete a times tables test in seconds is shown in the table… Time taken (t secs) Number of Students 30 ≤ t < 40 5 40 ≤ t < 50 11 50 ≤ t < 60 18 60 ≤ t < 70 6 70 ≤ t < 80 5 (a) Write down the modal class interval (1) (b) Calculate an estimate for the mean time taken to complete the test. (3) [4 marks] 8. In a bag there are red counters, white counters and black counters. There are four times as many red counters than white counters and twice as many white counters as black counters. Write down the ratio of red counters to white counters to black counters. [2 marks]