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Finding the Fourth Proportional to 1,238.60, 1,856.68 and 621.40

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Solution

The fourth proportional to 1,238.60, 1,856.68 and 621.40 is: 931.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,238.60 : 1,856.68 = 621.40 : x
  2. Step 2: Convert to fraction form
    1,238.60/1,856.68 = 621.40/x
  3. Step 3: Cross multiply
    1,238.60x = 1,856.68 × 621.40
  4. Step 4: Simplify right side
    1,238.60x = 1,153,740.95
  5. Step 5: Solve for x
    x = 1,153,740.95/1,238.60
  6. Step 6: Final answer
    x = 931.49

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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.