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Finding the Fourth Proportional to 1,379.32, 1,903.20 and 781.60

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Solution

The fourth proportional to 1,379.32, 1,903.20 and 781.60 is: 1,078.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,379.32 : 1,903.20 = 781.60 : x
  2. Step 2: Convert to fraction form
    1,379.32/1,903.20 = 781.60/x
  3. Step 3: Cross multiply
    1,379.32x = 1,903.20 × 781.60
  4. Step 4: Simplify right side
    1,379.32x = 1,487,541.12
  5. Step 5: Solve for x
    x = 1,487,541.12/1,379.32
  6. Step 6: Final answer
    x = 1,078.46

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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.