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Finding the Fourth Proportional to 678.99, 1,017.76 and 386.13

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Solution

The fourth proportional to 678.99, 1,017.76 and 386.13 is: 578.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.99 : 1,017.76 = 386.13 : x
  2. Step 2: Convert to fraction form
    678.99/1,017.76 = 386.13/x
  3. Step 3: Cross multiply
    678.99x = 1,017.76 × 386.13
  4. Step 4: Simplify right side
    678.99x = 392,987.67
  5. Step 5: Solve for x
    x = 392,987.67/678.99
  6. Step 6: Final answer
    x = 578.78

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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.