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Finding the Fourth Proportional to 1,128.65, 1,557.80 and 686.91

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Solution

The fourth proportional to 1,128.65, 1,557.80 and 686.91 is: 948.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.65 : 1,557.80 = 686.91 : x
  2. Step 2: Convert to fraction form
    1,128.65/1,557.80 = 686.91/x
  3. Step 3: Cross multiply
    1,128.65x = 1,557.80 × 686.91
  4. Step 4: Simplify right side
    1,128.65x = 1,070,064.96
  5. Step 5: Solve for x
    x = 1,070,064.96/1,128.65
  6. Step 6: Final answer
    x = 948.10

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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.