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Finding the Fourth Proportional to 1,230, 1,697.40 and 678

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Solution

The fourth proportional to 1,230, 1,697.40 and 678 is: 935.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,230 : 1,697.40 = 678 : x
  2. Step 2: Convert to fraction form
    1,230/1,697.40 = 678/x
  3. Step 3: Cross multiply
    1,230x = 1,697.40 × 678
  4. Step 4: Simplify right side
    1,230x = 1,150,837.20
  5. Step 5: Solve for x
    x = 1,150,837.20/1,230
  6. Step 6: Final answer
    x = 935.64

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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.