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Finding the Fourth Proportional to 1,120.44, 1,680.66 and 390

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Solution

The fourth proportional to 1,120.44, 1,680.66 and 390 is: 585

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.44 : 1,680.66 = 390 : x
  2. Step 2: Convert to fraction form
    1,120.44/1,680.66 = 390/x
  3. Step 3: Cross multiply
    1,120.44x = 1,680.66 × 390
  4. Step 4: Simplify right side
    1,120.44x = 655,457.40
  5. Step 5: Solve for x
    x = 655,457.40/1,120.44
  6. Step 6: Final answer
    x = 585

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Double scale
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Similar ratio
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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.