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Finding the Fourth Proportional to 685.11, 945.45 and 390.38

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Solution

The fourth proportional to 685.11, 945.45 and 390.38 is: 538.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.11 : 945.45 = 390.38 : x
  2. Step 2: Convert to fraction form
    685.11/945.45 = 390.38/x
  3. Step 3: Cross multiply
    685.11x = 945.45 × 390.38
  4. Step 4: Simplify right side
    685.11x = 369,080.04
  5. Step 5: Solve for x
    x = 369,080.04/685.11
  6. Step 6: Final answer
    x = 538.72

Related Problems

Find fourth proportional to 342.56, 472.73 and 195.19
Half scale
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Double scale
Find fourth proportional to 686.11, 946.83 and 391.38
Similar ratio
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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.