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Finding the Fourth Proportional to 1,321.26, 1,981.86 and 776.90

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Solution

The fourth proportional to 1,321.26, 1,981.86 and 776.90 is: 1,165.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.26 : 1,981.86 = 776.90 : x
  2. Step 2: Convert to fraction form
    1,321.26/1,981.86 = 776.90/x
  3. Step 3: Cross multiply
    1,321.26x = 1,981.86 × 776.90
  4. Step 4: Simplify right side
    1,321.26x = 1,539,697.12
  5. Step 5: Solve for x
    x = 1,539,697.12/1,321.26
  6. Step 6: Final answer
    x = 1,165.32

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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.