Final answer:
By finding the total scores for the first two tests (172) and the next three (288), and summing these, the combined total is 460. Dividing by the number of tests (5), we get an average score of 92. Therefore, option (b) is correct.
Step-by-step explanation:
To calculate the average score of all five tests, we must first find the total points for the first two and the last three tests separately, and then sum these totals to find the final combined average.
The student's average marks in the first two tests are 86, which means the total marks for two tests are 86 × 2 = 172 (since average = total points / number of tests).
Similarly, the average marks in the remaining three tests are 96, so the total marks for those three tests are 96 × 3 = 288.
Now, to find the average score in all five tests, we should add the totals of both groups of tests together and divide by the total number of tests, which is five.
So, the combined total marks for all five tests would be 172 + 288 = 460. The average for all five tests is then 460 / 5 = 92.
Therefore, the correct answer is (b) 92, which is the average score in all five tests.