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Finding the Fourth Proportional to 1,071.60, 1,479 and 678.78

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Solution

The fourth proportional to 1,071.60, 1,479 and 678.78 is: 936.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,071.60 : 1,479 = 678.78 : x
  2. Step 2: Convert to fraction form
    1,071.60/1,479 = 678.78/x
  3. Step 3: Cross multiply
    1,071.60x = 1,479 × 678.78
  4. Step 4: Simplify right side
    1,071.60x = 1,003,915.62
  5. Step 5: Solve for x
    x = 1,003,915.62/1,071.60
  6. Step 6: Final answer
    x = 936.84

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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.