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Finding the Fourth Proportional to 1,239.90, 1,711.32 and 820.32

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Solution

The fourth proportional to 1,239.90, 1,711.32 and 820.32 is: 1,132.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.90 : 1,711.32 = 820.32 : x
  2. Step 2: Convert to fraction form
    1,239.90/1,711.32 = 820.32/x
  3. Step 3: Cross multiply
    1,239.90x = 1,711.32 × 820.32
  4. Step 4: Simplify right side
    1,239.90x = 1,403,830.02
  5. Step 5: Solve for x
    x = 1,403,830.02/1,239.90
  6. Step 6: Final answer
    x = 1,132.21

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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.