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Finding the Fourth Proportional to 685.19, 945.63 and 390.53

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Solution

The fourth proportional to 685.19, 945.63 and 390.53 is: 538.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.19 : 945.63 = 390.53 : x
  2. Step 2: Convert to fraction form
    685.19/945.63 = 390.53/x
  3. Step 3: Cross multiply
    685.19x = 945.63 × 390.53
  4. Step 4: Simplify right side
    685.19x = 369,296.88
  5. Step 5: Solve for x
    x = 369,296.88/685.19
  6. Step 6: Final answer
    x = 538.97

Related Problems

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Half scale
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Double scale
Find fourth proportional to 686.19, 947.01 and 391.53
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.