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Finding the Fourth Proportional to 1,187.60, 1,638.90 and 663.68

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Solution

The fourth proportional to 1,187.60, 1,638.90 and 663.68 is: 915.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.60 : 1,638.90 = 663.68 : x
  2. Step 2: Convert to fraction form
    1,187.60/1,638.90 = 663.68/x
  3. Step 3: Cross multiply
    1,187.60x = 1,638.90 × 663.68
  4. Step 4: Simplify right side
    1,187.60x = 1,087,705.15
  5. Step 5: Solve for x
    x = 1,087,705.15/1,187.60
  6. Step 6: Final answer
    x = 915.89

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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.