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Finding the Fourth Proportional to 776, 1,070.40 and 621.12

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Solution

The fourth proportional to 776, 1,070.40 and 621.12 is: 856.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    776 : 1,070.40 = 621.12 : x
  2. Step 2: Convert to fraction form
    776/1,070.40 = 621.12/x
  3. Step 3: Cross multiply
    776x = 1,070.40 × 621.12
  4. Step 4: Simplify right side
    776x = 664,846.85
  5. Step 5: Solve for x
    x = 664,846.85/776
  6. Step 6: Final answer
    x = 856.76

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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.