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Finding the Fourth Proportional to 976.18, 1,345.89 and 643.99

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Solution

The fourth proportional to 976.18, 1,345.89 and 643.99 is: 887.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    976.18 : 1,345.89 = 643.99 : x
  2. Step 2: Convert to fraction form
    976.18/1,345.89 = 643.99/x
  3. Step 3: Cross multiply
    976.18x = 1,345.89 × 643.99
  4. Step 4: Simplify right side
    976.18x = 866,739.70
  5. Step 5: Solve for x
    x = 866,739.70/976.18
  6. Step 6: Final answer
    x = 887.89

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.