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Finding the Fourth Proportional to 8.70, 12 and 6.87

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Solution

The fourth proportional to 8.70, 12 and 6.87 is: 9.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.70 : 12 = 6.87 : x
  2. Step 2: Convert to fraction form
    8.70/12 = 6.87/x
  3. Step 3: Cross multiply
    8.70x = 12 × 6.87
  4. Step 4: Simplify right side
    8.70x = 82.44
  5. Step 5: Solve for x
    x = 82.44/8.70
  6. Step 6: Final answer
    x = 9.48

Related Problems

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Double scale
Find fourth proportional to 9.70, 13.38 and 7.87
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.