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Finding the Fourth Proportional to 989.88, 1,485.08 and 678.84

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Solution

The fourth proportional to 989.88, 1,485.08 and 678.84 is: 1,018.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.88 : 1,485.08 = 678.84 : x
  2. Step 2: Convert to fraction form
    989.88/1,485.08 = 678.84/x
  3. Step 3: Cross multiply
    989.88x = 1,485.08 × 678.84
  4. Step 4: Simplify right side
    989.88x = 1,008,131.71
  5. Step 5: Solve for x
    x = 1,008,131.71/989.88
  6. Step 6: Final answer
    x = 1,018.44

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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.