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Finding the Fourth Proportional to 1,320.74, 1,981.78 and 859.42

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Solution

The fourth proportional to 1,320.74, 1,981.78 and 859.42 is: 1,289.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.74 : 1,981.78 = 859.42 : x
  2. Step 2: Convert to fraction form
    1,320.74/1,981.78 = 859.42/x
  3. Step 3: Cross multiply
    1,320.74x = 1,981.78 × 859.42
  4. Step 4: Simplify right side
    1,320.74x = 1,703,181.37
  5. Step 5: Solve for x
    x = 1,703,181.37/1,320.74
  6. Step 6: Final answer
    x = 1,289.57

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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.