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Finding the Fourth Proportional to 685.56, 946 and 390.80

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Solution

The fourth proportional to 685.56, 946 and 390.80 is: 539.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.56 : 946 = 390.80 : x
  2. Step 2: Convert to fraction form
    685.56/946 = 390.80/x
  3. Step 3: Cross multiply
    685.56x = 946 × 390.80
  4. Step 4: Simplify right side
    685.56x = 369,696.80
  5. Step 5: Solve for x
    x = 369,696.80/685.56
  6. Step 6: Final answer
    x = 539.26

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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.