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Finding the Fourth Proportional to 642.06, 885.93 and 390

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Solution

The fourth proportional to 642.06, 885.93 and 390 is: 538.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.06 : 885.93 = 390 : x
  2. Step 2: Convert to fraction form
    642.06/885.93 = 390/x
  3. Step 3: Cross multiply
    642.06x = 885.93 × 390
  4. Step 4: Simplify right side
    642.06x = 345,512.70
  5. Step 5: Solve for x
    x = 345,512.70/642.06
  6. Step 6: Final answer
    x = 538.13

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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.