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Finding the Fourth Proportional to 21.70, 29.86 and 20.76

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Solution

The fourth proportional to 21.70, 29.86 and 20.76 is: 28.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.70 : 29.86 = 20.76 : x
  2. Step 2: Convert to fraction form
    21.70/29.86 = 20.76/x
  3. Step 3: Cross multiply
    21.70x = 29.86 × 20.76
  4. Step 4: Simplify right side
    21.70x = 619.89
  5. Step 5: Solve for x
    x = 619.89/21.70
  6. Step 6: Final answer
    x = 28.57

Related Problems

Find fourth proportional to 10.85, 14.93 and 10.38
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Double scale
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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.