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Finding the Fourth Proportional to 1,128.54, 1,557.86 and 686.60

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Solution

The fourth proportional to 1,128.54, 1,557.86 and 686.60 is: 947.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.54 : 1,557.86 = 686.60 : x
  2. Step 2: Convert to fraction form
    1,128.54/1,557.86 = 686.60/x
  3. Step 3: Cross multiply
    1,128.54x = 1,557.86 × 686.60
  4. Step 4: Simplify right side
    1,128.54x = 1,069,626.68
  5. Step 5: Solve for x
    x = 1,069,626.68/1,128.54
  6. Step 6: Final answer
    x = 947.80

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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.