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Finding the Fourth Proportional to 259, 388.56 and 85.68

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Solution

The fourth proportional to 259, 388.56 and 85.68 is: 128.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    259 : 388.56 = 85.68 : x
  2. Step 2: Convert to fraction form
    259/388.56 = 85.68/x
  3. Step 3: Cross multiply
    259x = 388.56 × 85.68
  4. Step 4: Simplify right side
    259x = 33,291.82
  5. Step 5: Solve for x
    x = 33,291.82/259
  6. Step 6: Final answer
    x = 128.54

Related Problems

Find fourth proportional to 129.50, 194.28 and 42.84
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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.