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Finding the Fourth Proportional to 890.40, 1,337.20 and 647.20

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Solution

The fourth proportional to 890.40, 1,337.20 and 647.20 is: 971.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    890.40 : 1,337.20 = 647.20 : x
  2. Step 2: Convert to fraction form
    890.40/1,337.20 = 647.20/x
  3. Step 3: Cross multiply
    890.40x = 1,337.20 × 647.20
  4. Step 4: Simplify right side
    890.40x = 865,435.84
  5. Step 5: Solve for x
    x = 865,435.84/890.40
  6. Step 6: Final answer
    x = 971.96

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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.