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Finding the Fourth Proportional to 1,386.86, 2,080.42 and 399.72

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Solution

The fourth proportional to 1,386.86, 2,080.42 and 399.72 is: 599.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.86 : 2,080.42 = 399.72 : x
  2. Step 2: Convert to fraction form
    1,386.86/2,080.42 = 399.72/x
  3. Step 3: Cross multiply
    1,386.86x = 2,080.42 × 399.72
  4. Step 4: Simplify right side
    1,386.86x = 831,592.28
  5. Step 5: Solve for x
    x = 831,592.28/1,386.86
  6. Step 6: Final answer
    x = 599.62

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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.