Question: Tatuya, Ivanna, and Dorothy took a quiz together. Tatuya scored twice as much as Ivanna, and Ivanna scored 3/5 times as many marks as Dorothy. If Dorothy scored 90 marks, calculate the average marks scored by the three. Think carefully first, then make a decision:
Since Dorothy scored 90 marks, and Ivanna scored 3 / 5 times as many marks, Ivanna scored 3 / 5 * 90 = 54 marks. Together, Dorothy and Ivanna scored a total of 54 + 90 = 144 marks. If Tayuta scored twice as many marks as Ivanna, she scored 2 * 54 = 108 marks. The total marks the three scored altogether is 108 + 144 = 252 marks. The average marks for the three are 252 / 3 = 84 marks. So the answer is 84.