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Finding the Fourth Proportional to 678.90, 1,017.80 and 313.59

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Solution

The fourth proportional to 678.90, 1,017.80 and 313.59 is: 470.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.90 : 1,017.80 = 313.59 : x
  2. Step 2: Convert to fraction form
    678.90/1,017.80 = 313.59/x
  3. Step 3: Cross multiply
    678.90x = 1,017.80 × 313.59
  4. Step 4: Simplify right side
    678.90x = 319,170.33
  5. Step 5: Solve for x
    x = 319,170.33/678.90
  6. Step 6: Final answer
    x = 470.13

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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.