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Finding the Fourth Proportional to 740.12, 1,021.79 and 491.78

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Solution

The fourth proportional to 740.12, 1,021.79 and 491.78 is: 678.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    740.12 : 1,021.79 = 491.78 : x
  2. Step 2: Convert to fraction form
    740.12/1,021.79 = 491.78/x
  3. Step 3: Cross multiply
    740.12x = 1,021.79 × 491.78
  4. Step 4: Simplify right side
    740.12x = 502,495.89
  5. Step 5: Solve for x
    x = 502,495.89/740.12
  6. Step 6: Final answer
    x = 678.94

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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.