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Finding the Fourth Proportional to 751.42, 1,039.80 and 640.72

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Solution

The fourth proportional to 751.42, 1,039.80 and 640.72 is: 886.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    751.42 : 1,039.80 = 640.72 : x
  2. Step 2: Convert to fraction form
    751.42/1,039.80 = 640.72/x
  3. Step 3: Cross multiply
    751.42x = 1,039.80 × 640.72
  4. Step 4: Simplify right side
    751.42x = 666,220.66
  5. Step 5: Solve for x
    x = 666,220.66/751.42
  6. Step 6: Final answer
    x = 886.62

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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.