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Finding the Fourth Proportional to 678.40, 1,016.48 and 621.66

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Solution

The fourth proportional to 678.40, 1,016.48 and 621.66 is: 931.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.40 : 1,016.48 = 621.66 : x
  2. Step 2: Convert to fraction form
    678.40/1,016.48 = 621.66/x
  3. Step 3: Cross multiply
    678.40x = 1,016.48 × 621.66
  4. Step 4: Simplify right side
    678.40x = 631,904.61
  5. Step 5: Solve for x
    x = 631,904.61/678.40
  6. Step 6: Final answer
    x = 931.46

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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.