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Finding the Fourth Proportional to 1,391.92, 1,921.64 and 919.68

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Solution

The fourth proportional to 1,391.92, 1,921.64 and 919.68 is: 1,269.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.92 : 1,921.64 = 919.68 : x
  2. Step 2: Convert to fraction form
    1,391.92/1,921.64 = 919.68/x
  3. Step 3: Cross multiply
    1,391.92x = 1,921.64 × 919.68
  4. Step 4: Simplify right side
    1,391.92x = 1,767,293.88
  5. Step 5: Solve for x
    x = 1,767,293.88/1,391.92
  6. Step 6: Final answer
    x = 1,269.68

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1.5x scale

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.