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Finding the Fourth Proportional to 1,123.20, 1,685.80 and 660.40

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Solution

The fourth proportional to 1,123.20, 1,685.80 and 660.40 is: 991.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,123.20 : 1,685.80 = 660.40 : x
  2. Step 2: Convert to fraction form
    1,123.20/1,685.80 = 660.40/x
  3. Step 3: Cross multiply
    1,123.20x = 1,685.80 × 660.40
  4. Step 4: Simplify right side
    1,123.20x = 1,113,302.32
  5. Step 5: Solve for x
    x = 1,113,302.32/1,123.20
  6. Step 6: Final answer
    x = 991.19

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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.