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Finding the Fourth Proportional to 874.32, 1,312.40 and 643.48

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Solution

The fourth proportional to 874.32, 1,312.40 and 643.48 is: 965.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    874.32 : 1,312.40 = 643.48 : x
  2. Step 2: Convert to fraction form
    874.32/1,312.40 = 643.48/x
  3. Step 3: Cross multiply
    874.32x = 1,312.40 × 643.48
  4. Step 4: Simplify right side
    874.32x = 844,503.15
  5. Step 5: Solve for x
    x = 844,503.15/874.32
  6. Step 6: Final answer
    x = 965.90

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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.