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Finding the Fourth Proportional to 260.63, 390.98 and 78

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Solution

The fourth proportional to 260.63, 390.98 and 78 is: 117.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.63 : 390.98 = 78 : x
  2. Step 2: Convert to fraction form
    260.63/390.98 = 78/x
  3. Step 3: Cross multiply
    260.63x = 390.98 × 78
  4. Step 4: Simplify right side
    260.63x = 30,496.44
  5. Step 5: Solve for x
    x = 30,496.44/260.63
  6. Step 6: Final answer
    x = 117.01

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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.