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Finding the Fourth Proportional to 1,121.22, 1,681.34 and 390.42

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Solution

The fourth proportional to 1,121.22, 1,681.34 and 390.42 is: 585.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.22 : 1,681.34 = 390.42 : x
  2. Step 2: Convert to fraction form
    1,121.22/1,681.34 = 390.42/x
  3. Step 3: Cross multiply
    1,121.22x = 1,681.34 × 390.42
  4. Step 4: Simplify right side
    1,121.22x = 656,426.81
  5. Step 5: Solve for x
    x = 656,426.81/1,121.22
  6. Step 6: Final answer
    x = 585.46

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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.