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Finding the Fourth Proportional to 630.78, 870.75 and 491.28

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Solution

The fourth proportional to 630.78, 870.75 and 491.28 is: 678.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    630.78 : 870.75 = 491.28 : x
  2. Step 2: Convert to fraction form
    630.78/870.75 = 491.28/x
  3. Step 3: Cross multiply
    630.78x = 870.75 × 491.28
  4. Step 4: Simplify right side
    630.78x = 427,782.06
  5. Step 5: Solve for x
    x = 427,782.06/630.78
  6. Step 6: Final answer
    x = 678.18

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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.