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Finding the Fourth Proportional to 786.78, 1,085.76 and 492.21

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Solution

The fourth proportional to 786.78, 1,085.76 and 492.21 is: 679.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.78 : 1,085.76 = 492.21 : x
  2. Step 2: Convert to fraction form
    786.78/1,085.76 = 492.21/x
  3. Step 3: Cross multiply
    786.78x = 1,085.76 × 492.21
  4. Step 4: Simplify right side
    786.78x = 534,421.93
  5. Step 5: Solve for x
    x = 534,421.93/786.78
  6. Step 6: Final answer
    x = 679.25

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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.