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Finding the Fourth Proportional to 859.80, 1,288.80 and 426.72

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Solution

The fourth proportional to 859.80, 1,288.80 and 426.72 is: 639.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.80 : 1,288.80 = 426.72 : x
  2. Step 2: Convert to fraction form
    859.80/1,288.80 = 426.72/x
  3. Step 3: Cross multiply
    859.80x = 1,288.80 × 426.72
  4. Step 4: Simplify right side
    859.80x = 549,956.74
  5. Step 5: Solve for x
    x = 549,956.74/859.80
  6. Step 6: Final answer
    x = 639.63

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.