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Finding the Fourth Proportional to 777.12, 1,072.40 and 427.80

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Solution

The fourth proportional to 777.12, 1,072.40 and 427.80 is: 590.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    777.12 : 1,072.40 = 427.80 : x
  2. Step 2: Convert to fraction form
    777.12/1,072.40 = 427.80/x
  3. Step 3: Cross multiply
    777.12x = 1,072.40 × 427.80
  4. Step 4: Simplify right side
    777.12x = 458,772.72
  5. Step 5: Solve for x
    x = 458,772.72/777.12
  6. Step 6: Final answer
    x = 590.35

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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.