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Finding the Fourth Proportional to 1,221.86, 1,685.53 and 778.99

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Solution

The fourth proportional to 1,221.86, 1,685.53 and 778.99 is: 1,074.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.86 : 1,685.53 = 778.99 : x
  2. Step 2: Convert to fraction form
    1,221.86/1,685.53 = 778.99/x
  3. Step 3: Cross multiply
    1,221.86x = 1,685.53 × 778.99
  4. Step 4: Simplify right side
    1,221.86x = 1,313,011.01
  5. Step 5: Solve for x
    x = 1,313,011.01/1,221.86
  6. Step 6: Final answer
    x = 1,074.60

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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.