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Finding the Fourth Proportional to 919.92, 1,268.53 and 640.47

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Solution

The fourth proportional to 919.92, 1,268.53 and 640.47 is: 883.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.92 : 1,268.53 = 640.47 : x
  2. Step 2: Convert to fraction form
    919.92/1,268.53 = 640.47/x
  3. Step 3: Cross multiply
    919.92x = 1,268.53 × 640.47
  4. Step 4: Simplify right side
    919.92x = 812,455.41
  5. Step 5: Solve for x
    x = 812,455.41/919.92
  6. Step 6: Final answer
    x = 883.18

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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.