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Finding the Fourth Proportional to 1,385.85, 2,080.80 and 840.32

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Solution

The fourth proportional to 1,385.85, 2,080.80 and 840.32 is: 1,261.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,385.85 : 2,080.80 = 840.32 : x
  2. Step 2: Convert to fraction form
    1,385.85/2,080.80 = 840.32/x
  3. Step 3: Cross multiply
    1,385.85x = 2,080.80 × 840.32
  4. Step 4: Simplify right side
    1,385.85x = 1,748,527.45
  5. Step 5: Solve for x
    x = 1,748,527.45/1,385.85
  6. Step 6: Final answer
    x = 1,261.70

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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.