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Finding the Fourth Proportional to 485.78, 670.38 and 278.78

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Solution

The fourth proportional to 485.78, 670.38 and 278.78 is: 384.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.78 : 670.38 = 278.78 : x
  2. Step 2: Convert to fraction form
    485.78/670.38 = 278.78/x
  3. Step 3: Cross multiply
    485.78x = 670.38 × 278.78
  4. Step 4: Simplify right side
    485.78x = 186,888.54
  5. Step 5: Solve for x
    x = 186,888.54/485.78
  6. Step 6: Final answer
    x = 384.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.