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Finding the Fourth Proportional to 1,289.92, 1,935.12 and 780.16

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Solution

The fourth proportional to 1,289.92, 1,935.12 and 780.16 is: 1,170.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.92 : 1,935.12 = 780.16 : x
  2. Step 2: Convert to fraction form
    1,289.92/1,935.12 = 780.16/x
  3. Step 3: Cross multiply
    1,289.92x = 1,935.12 × 780.16
  4. Step 4: Simplify right side
    1,289.92x = 1,509,703.22
  5. Step 5: Solve for x
    x = 1,509,703.22/1,289.92
  6. Step 6: Final answer
    x = 1,170.39

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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.