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Finding the Fourth Proportional to 1,386.67, 2,079.60 and 520.78

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Solution

The fourth proportional to 1,386.67, 2,079.60 and 520.78 is: 781.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.67 : 2,079.60 = 520.78 : x
  2. Step 2: Convert to fraction form
    1,386.67/2,079.60 = 520.78/x
  3. Step 3: Cross multiply
    1,386.67x = 2,079.60 × 520.78
  4. Step 4: Simplify right side
    1,386.67x = 1,083,014.09
  5. Step 5: Solve for x
    x = 1,083,014.09/1,386.67
  6. Step 6: Final answer
    x = 781.02

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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.