Finding the Fourth Proportional to 81.20, 121.68 and 79.20
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Solution
The fourth proportional to 81.20, 121.68 and 79.20 is: 118.68
Step by Step Solution
- Step 1: Write the proportion equation
81.20 : 121.68 = 79.20 : x - Step 2: Convert to fraction form
81.20/121.68 = 79.20/x - Step 3: Cross multiply
81.20x = 121.68 × 79.20 - Step 4: Simplify right side
81.20x = 9,637.06 - Step 5: Solve for x
x = 9,637.06/81.20 - Step 6: Final answer
x = 118.68
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Why These Related Problems?
These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.