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Finding the Fourth Proportional to 1,128.88, 1,557.85 and 686.70

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Solution

The fourth proportional to 1,128.88, 1,557.85 and 686.70 is: 947.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.88 : 1,557.85 = 686.70 : x
  2. Step 2: Convert to fraction form
    1,128.88/1,557.85 = 686.70/x
  3. Step 3: Cross multiply
    1,128.88x = 1,557.85 × 686.70
  4. Step 4: Simplify right side
    1,128.88x = 1,069,767.81
  5. Step 5: Solve for x
    x = 1,069,767.81/1,128.88
  6. Step 6: Final answer
    x = 947.64

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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.