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Finding the Fourth Proportional to 678.84, 1,017.18 and 390.60

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Solution

The fourth proportional to 678.84, 1,017.18 and 390.60 is: 585.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.84 : 1,017.18 = 390.60 : x
  2. Step 2: Convert to fraction form
    678.84/1,017.18 = 390.60/x
  3. Step 3: Cross multiply
    678.84x = 1,017.18 × 390.60
  4. Step 4: Simplify right side
    678.84x = 397,310.51
  5. Step 5: Solve for x
    x = 397,310.51/678.84
  6. Step 6: Final answer
    x = 585.28

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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.