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Finding the Fourth Proportional to 491.79, 678.74 and 317.64

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Solution

The fourth proportional to 491.79, 678.74 and 317.64 is: 438.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    491.79 : 678.74 = 317.64 : x
  2. Step 2: Convert to fraction form
    491.79/678.74 = 317.64/x
  3. Step 3: Cross multiply
    491.79x = 678.74 × 317.64
  4. Step 4: Simplify right side
    491.79x = 215,594.97
  5. Step 5: Solve for x
    x = 215,594.97/491.79
  6. Step 6: Final answer
    x = 438.39

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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.