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Finding the Fourth Proportional to 684.77, 945.14 and 390.20

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Solution

The fourth proportional to 684.77, 945.14 and 390.20 is: 538.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    684.77 : 945.14 = 390.20 : x
  2. Step 2: Convert to fraction form
    684.77/945.14 = 390.20/x
  3. Step 3: Cross multiply
    684.77x = 945.14 × 390.20
  4. Step 4: Simplify right side
    684.77x = 368,786.95
  5. Step 5: Solve for x
    x = 368,786.95/684.77
  6. Step 6: Final answer
    x = 538.56

Related Problems

Find fourth proportional to 342.38, 472.57 and 195.10
Half scale
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Double scale
Find fourth proportional to 685.77, 946.52 and 391.20
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.