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Finding the Fourth Proportional to 780.90, 1,176.72 and 646.94

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Solution

The fourth proportional to 780.90, 1,176.72 and 646.94 is: 974.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.90 : 1,176.72 = 646.94 : x
  2. Step 2: Convert to fraction form
    780.90/1,176.72 = 646.94/x
  3. Step 3: Cross multiply
    780.90x = 1,176.72 × 646.94
  4. Step 4: Simplify right side
    780.90x = 761,261.35
  5. Step 5: Solve for x
    x = 761,261.35/780.90
  6. Step 6: Final answer
    x = 974.85

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.