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Finding the Fourth Proportional to 770.40, 1,155.60 and 641.76

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Solution

The fourth proportional to 770.40, 1,155.60 and 641.76 is: 962.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    770.40 : 1,155.60 = 641.76 : x
  2. Step 2: Convert to fraction form
    770.40/1,155.60 = 641.76/x
  3. Step 3: Cross multiply
    770.40x = 1,155.60 × 641.76
  4. Step 4: Simplify right side
    770.40x = 741,617.86
  5. Step 5: Solve for x
    x = 741,617.86/770.40
  6. Step 6: Final answer
    x = 962.64

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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.