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Finding the Fourth Proportional to 1,139.64, 1,572.86 and 642.30

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Solution

The fourth proportional to 1,139.64, 1,572.86 and 642.30 is: 886.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.64 : 1,572.86 = 642.30 : x
  2. Step 2: Convert to fraction form
    1,139.64/1,572.86 = 642.30/x
  3. Step 3: Cross multiply
    1,139.64x = 1,572.86 × 642.30
  4. Step 4: Simplify right side
    1,139.64x = 1,010,247.98
  5. Step 5: Solve for x
    x = 1,010,247.98/1,139.64
  6. Step 6: Final answer
    x = 886.46

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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.