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Finding the Fourth Proportional to 685.19, 945.34 and 390.25

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Solution

The fourth proportional to 685.19, 945.34 and 390.25 is: 538.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.19 : 945.34 = 390.25 : x
  2. Step 2: Convert to fraction form
    685.19/945.34 = 390.25/x
  3. Step 3: Cross multiply
    685.19x = 945.34 × 390.25
  4. Step 4: Simplify right side
    685.19x = 368,919.83
  5. Step 5: Solve for x
    x = 368,919.83/685.19
  6. Step 6: Final answer
    x = 538.42

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1.5x scale

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.