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Finding the Fourth Proportional to 873.90, 1,312.20 and 509.40

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Solution

The fourth proportional to 873.90, 1,312.20 and 509.40 is: 764.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    873.90 : 1,312.20 = 509.40 : x
  2. Step 2: Convert to fraction form
    873.90/1,312.20 = 509.40/x
  3. Step 3: Cross multiply
    873.90x = 1,312.20 × 509.40
  4. Step 4: Simplify right side
    873.90x = 668,434.68
  5. Step 5: Solve for x
    x = 668,434.68/873.90
  6. Step 6: Final answer
    x = 764.89

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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.