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Finding the Fourth Proportional to 1,108.72, 1,529.76 and 642.88

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Solution

The fourth proportional to 1,108.72, 1,529.76 and 642.88 is: 887.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,108.72 : 1,529.76 = 642.88 : x
  2. Step 2: Convert to fraction form
    1,108.72/1,529.76 = 642.88/x
  3. Step 3: Cross multiply
    1,108.72x = 1,529.76 × 642.88
  4. Step 4: Simplify right side
    1,108.72x = 983,452.11
  5. Step 5: Solve for x
    x = 983,452.11/1,108.72
  6. Step 6: Final answer
    x = 887.02

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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.