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Finding the Fourth Proportional to 780.76, 1,076.34 and 640.18

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Solution

The fourth proportional to 780.76, 1,076.34 and 640.18 is: 882.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.76 : 1,076.34 = 640.18 : x
  2. Step 2: Convert to fraction form
    780.76/1,076.34 = 640.18/x
  3. Step 3: Cross multiply
    780.76x = 1,076.34 × 640.18
  4. Step 4: Simplify right side
    780.76x = 689,051.34
  5. Step 5: Solve for x
    x = 689,051.34/780.76
  6. Step 6: Final answer
    x = 882.54

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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.