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Finding the Fourth Proportional to 1,386.90, 2,079.81 and 521.28

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Solution

The fourth proportional to 1,386.90, 2,079.81 and 521.28 is: 781.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.90 : 2,079.81 = 521.28 : x
  2. Step 2: Convert to fraction form
    1,386.90/2,079.81 = 521.28/x
  3. Step 3: Cross multiply
    1,386.90x = 2,079.81 × 521.28
  4. Step 4: Simplify right side
    1,386.90x = 1,084,163.36
  5. Step 5: Solve for x
    x = 1,084,163.36/1,386.90
  6. Step 6: Final answer
    x = 781.72

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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.