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Finding the Fourth Proportional to 561.45, 774.80 and 312.78

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Solution

The fourth proportional to 561.45, 774.80 and 312.78 is: 431.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    561.45 : 774.80 = 312.78 : x
  2. Step 2: Convert to fraction form
    561.45/774.80 = 312.78/x
  3. Step 3: Cross multiply
    561.45x = 774.80 × 312.78
  4. Step 4: Simplify right side
    561.45x = 242,344.46
  5. Step 5: Solve for x
    x = 242,344.46/561.45
  6. Step 6: Final answer
    x = 431.64

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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.