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Finding the Fourth Proportional to 1,128.53, 1,557.65 and 686.80

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Solution

The fourth proportional to 1,128.53, 1,557.65 and 686.80 is: 947.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.53 : 1,557.65 = 686.80 : x
  2. Step 2: Convert to fraction form
    1,128.53/1,557.65 = 686.80/x
  3. Step 3: Cross multiply
    1,128.53x = 1,557.65 × 686.80
  4. Step 4: Simplify right side
    1,128.53x = 1,069,791.84
  5. Step 5: Solve for x
    x = 1,069,791.84/1,128.53
  6. Step 6: Final answer
    x = 947.96

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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.