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Finding the Fourth Proportional to 780.60, 1,165.76 and 678.20

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Solution

The fourth proportional to 780.60, 1,165.76 and 678.20 is: 1,012.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.60 : 1,165.76 = 678.20 : x
  2. Step 2: Convert to fraction form
    780.60/1,165.76 = 678.20/x
  3. Step 3: Cross multiply
    780.60x = 1,165.76 × 678.20
  4. Step 4: Simplify right side
    780.60x = 790,618.43
  5. Step 5: Solve for x
    x = 790,618.43/780.60
  6. Step 6: Final answer
    x = 1,012.83

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.