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Finding the Fourth Proportional to 1,120.66, 1,680.84 and 390.19

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Solution

The fourth proportional to 1,120.66, 1,680.84 and 390.19 is: 585.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.66 : 1,680.84 = 390.19 : x
  2. Step 2: Convert to fraction form
    1,120.66/1,680.84 = 390.19/x
  3. Step 3: Cross multiply
    1,120.66x = 1,680.84 × 390.19
  4. Step 4: Simplify right side
    1,120.66x = 655,846.96
  5. Step 5: Solve for x
    x = 655,846.96/1,120.66
  6. Step 6: Final answer
    x = 585.23

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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.