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Finding the Fourth Proportional to 875.90, 1,311.15 and 778.70

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Solution

The fourth proportional to 875.90, 1,311.15 and 778.70 is: 1,165.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    875.90 : 1,311.15 = 778.70 : x
  2. Step 2: Convert to fraction form
    875.90/1,311.15 = 778.70/x
  3. Step 3: Cross multiply
    875.90x = 1,311.15 × 778.70
  4. Step 4: Simplify right side
    875.90x = 1,020,992.51
  5. Step 5: Solve for x
    x = 1,020,992.51/875.90
  6. Step 6: Final answer
    x = 1,165.65

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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.