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Finding the Fourth Proportional to 521.66, 781.49 and 390.99

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Solution

The fourth proportional to 521.66, 781.49 and 390.99 is: 585.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.66 : 781.49 = 390.99 : x
  2. Step 2: Convert to fraction form
    521.66/781.49 = 390.99/x
  3. Step 3: Cross multiply
    521.66x = 781.49 × 390.99
  4. Step 4: Simplify right side
    521.66x = 305,554.78
  5. Step 5: Solve for x
    x = 305,554.78/521.66
  6. Step 6: Final answer
    x = 585.74

Related Problems

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Half scale
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Double scale
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Similar ratio
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.