A student scores 80, 85, 90, and 95 in four exams. What score does he need in th

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Question: A student scores 80, 85, 90, and 95 in four exams. What score does he need in the fifth exam to achieve an average of 90?

Options:

Correct Answer: 100

Solution:

Mean = (80 + 85 + 90 + 95 + x) / 5 = 90.\\n\\n350 + x = 450\\n\\nx = 450 - 350 = 100.

A student scores 80, 85, 90, and 95 in four exams. What score does he need in the fifth exam to achieve an average of 90?

A student scores 80, 85, 90, and 95 in four exams. What score does he need in the fifth exam to achieve an average of 90?

Step 1: Add the scores of the first four exams: 80 + 85 + 90 + 95.
Step 2: Calculate the total from Step 1: 80 + 85 = 165, then 165 + 90 = 255, and finally 255 + 95 = 350.
Step 3: Let 'x' be the score needed in the fifth exam.
Step 4: To find the average, we use the formula: (total of all scores) / (number of exams). We want this average to be 90.
Step 5: Set up the equation: (350 + x) / 5 = 90.
Step 6: Multiply both sides of the equation by 5 to eliminate the fraction: 350 + x = 450.
Step 7: Solve for 'x' by subtracting 350 from both sides: x = 450 - 350.
Step 8: Calculate the result: x = 100.

Mean Calculation – Understanding how to calculate the average (mean) of a set of numbers by summing them and dividing by the count.
Algebraic Manipulation – Using algebra to solve for an unknown variable in an equation.