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Finding the Fourth Proportional to 919.81, 1,378.77 and 687.07

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Solution

The fourth proportional to 919.81, 1,378.77 and 687.07 is: 1,029.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.81 : 1,378.77 = 687.07 : x
  2. Step 2: Convert to fraction form
    919.81/1,378.77 = 687.07/x
  3. Step 3: Cross multiply
    919.81x = 1,378.77 × 687.07
  4. Step 4: Simplify right side
    919.81x = 947,311.50
  5. Step 5: Solve for x
    x = 947,311.50/919.81
  6. Step 6: Final answer
    x = 1,029.90

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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.