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Finding the Fourth Proportional to 1,128.76, 1,687.13 and 981.32

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Solution

The fourth proportional to 1,128.76, 1,687.13 and 981.32 is: 1,466.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.76 : 1,687.13 = 981.32 : x
  2. Step 2: Convert to fraction form
    1,128.76/1,687.13 = 981.32/x
  3. Step 3: Cross multiply
    1,128.76x = 1,687.13 × 981.32
  4. Step 4: Simplify right side
    1,128.76x = 1,655,614.41
  5. Step 5: Solve for x
    x = 1,655,614.41/1,128.76
  6. Step 6: Final answer
    x = 1,466.76

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.