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Finding the Fourth Proportional to 1,120.89, 1,681.11 and 390.51

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Solution

The fourth proportional to 1,120.89, 1,681.11 and 390.51 is: 585.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.89 : 1,681.11 = 390.51 : x
  2. Step 2: Convert to fraction form
    1,120.89/1,681.11 = 390.51/x
  3. Step 3: Cross multiply
    1,120.89x = 1,681.11 × 390.51
  4. Step 4: Simplify right side
    1,120.89x = 656,490.27
  5. Step 5: Solve for x
    x = 656,490.27/1,120.89
  6. Step 6: Final answer
    x = 585.69

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Double scale
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1.5x scale

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.