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Finding the Fourth Proportional to 1,012.95, 1,397.48 and 639.78

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Solution

The fourth proportional to 1,012.95, 1,397.48 and 639.78 is: 882.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,012.95 : 1,397.48 = 639.78 : x
  2. Step 2: Convert to fraction form
    1,012.95/1,397.48 = 639.78/x
  3. Step 3: Cross multiply
    1,012.95x = 1,397.48 × 639.78
  4. Step 4: Simplify right side
    1,012.95x = 894,079.75
  5. Step 5: Solve for x
    x = 894,079.75/1,012.95
  6. Step 6: Final answer
    x = 882.65

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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.