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Finding the Fourth Proportional to 770.72, 1,066.20 and 678.80

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Solution

The fourth proportional to 770.72, 1,066.20 and 678.80 is: 939.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    770.72 : 1,066.20 = 678.80 : x
  2. Step 2: Convert to fraction form
    770.72/1,066.20 = 678.80/x
  3. Step 3: Cross multiply
    770.72x = 1,066.20 × 678.80
  4. Step 4: Simplify right side
    770.72x = 723,736.56
  5. Step 5: Solve for x
    x = 723,736.56/770.72
  6. Step 6: Final answer
    x = 939.04

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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.