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Finding the Fourth Proportional to 1,279.92, 1,920 and 770.16

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Solution

The fourth proportional to 1,279.92, 1,920 and 770.16 is: 1,155.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,279.92 : 1,920 = 770.16 : x
  2. Step 2: Convert to fraction form
    1,279.92/1,920 = 770.16/x
  3. Step 3: Cross multiply
    1,279.92x = 1,920 × 770.16
  4. Step 4: Simplify right side
    1,279.92x = 1,478,707.20
  5. Step 5: Solve for x
    x = 1,478,707.20/1,279.92
  6. Step 6: Final answer
    x = 1,155.31

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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.