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Finding the Fourth Proportional to 1,121.01, 1,681.61 and 390.57

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Solution

The fourth proportional to 1,121.01, 1,681.61 and 390.57 is: 585.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.01 : 1,681.61 = 390.57 : x
  2. Step 2: Convert to fraction form
    1,121.01/1,681.61 = 390.57/x
  3. Step 3: Cross multiply
    1,121.01x = 1,681.61 × 390.57
  4. Step 4: Simplify right side
    1,121.01x = 656,784.46
  5. Step 5: Solve for x
    x = 656,784.46/1,121.01
  6. Step 6: Final answer
    x = 585.89

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Double scale
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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.