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Finding the Fourth Proportional to 1,187.55, 1,780.76 and 660.40

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Solution

The fourth proportional to 1,187.55, 1,780.76 and 660.40 is: 990.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.55 : 1,780.76 = 660.40 : x
  2. Step 2: Convert to fraction form
    1,187.55/1,780.76 = 660.40/x
  3. Step 3: Cross multiply
    1,187.55x = 1,780.76 × 660.40
  4. Step 4: Simplify right side
    1,187.55x = 1,176,011.10
  5. Step 5: Solve for x
    x = 1,176,011.10/1,187.55
  6. Step 6: Final answer
    x = 990.28

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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.