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Finding the Fourth Proportional to 918.60, 1,378.35 and 431.57

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Solution

The fourth proportional to 918.60, 1,378.35 and 431.57 is: 647.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.60 : 1,378.35 = 431.57 : x
  2. Step 2: Convert to fraction form
    918.60/1,378.35 = 431.57/x
  3. Step 3: Cross multiply
    918.60x = 1,378.35 × 431.57
  4. Step 4: Simplify right side
    918.60x = 594,854.51
  5. Step 5: Solve for x
    x = 594,854.51/918.60
  6. Step 6: Final answer
    x = 647.57

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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.