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Finding the Fourth Proportional to 1,125.75, 1,689.50 and 781.50

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Solution

The fourth proportional to 1,125.75, 1,689.50 and 781.50 is: 1,172.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,125.75 : 1,689.50 = 781.50 : x
  2. Step 2: Convert to fraction form
    1,125.75/1,689.50 = 781.50/x
  3. Step 3: Cross multiply
    1,125.75x = 1,689.50 × 781.50
  4. Step 4: Simplify right side
    1,125.75x = 1,320,340.34
  5. Step 5: Solve for x
    x = 1,320,340.34/1,125.75
  6. Step 6: Final answer
    x = 1,172.85

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1.5x scale

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.