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Finding the Fourth Proportional to 840.40, 1,159.08 and 620.80

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Solution

The fourth proportional to 840.40, 1,159.08 and 620.80 is: 856.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.40 : 1,159.08 = 620.80 : x
  2. Step 2: Convert to fraction form
    840.40/1,159.08 = 620.80/x
  3. Step 3: Cross multiply
    840.40x = 1,159.08 × 620.80
  4. Step 4: Simplify right side
    840.40x = 719,556.86
  5. Step 5: Solve for x
    x = 719,556.86/840.40
  6. Step 6: Final answer
    x = 856.21

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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.