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Finding the Fourth Proportional to 212.50, 318.80 and 115

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Solution

The fourth proportional to 212.50, 318.80 and 115 is: 172.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.50 : 318.80 = 115 : x
  2. Step 2: Convert to fraction form
    212.50/318.80 = 115/x
  3. Step 3: Cross multiply
    212.50x = 318.80 × 115
  4. Step 4: Simplify right side
    212.50x = 36,662
  5. Step 5: Solve for x
    x = 36,662/212.50
  6. Step 6: Final answer
    x = 172.53

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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.