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Finding the Fourth Proportional to 21.81, 30.10 and 13.19

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Solution

The fourth proportional to 21.81, 30.10 and 13.19 is: 18.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.81 : 30.10 = 13.19 : x
  2. Step 2: Convert to fraction form
    21.81/30.10 = 13.19/x
  3. Step 3: Cross multiply
    21.81x = 30.10 × 13.19
  4. Step 4: Simplify right side
    21.81x = 397.02
  5. Step 5: Solve for x
    x = 397.02/21.81
  6. Step 6: Final answer
    x = 18.20

Related Problems

Find fourth proportional to 10.91, 15.05 and 6.60
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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.