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Finding the Fourth Proportional to 21.79, 30 and 19.05

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Solution

The fourth proportional to 21.79, 30 and 19.05 is: 26.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.79 : 30 = 19.05 : x
  2. Step 2: Convert to fraction form
    21.79/30 = 19.05/x
  3. Step 3: Cross multiply
    21.79x = 30 × 19.05
  4. Step 4: Simplify right side
    21.79x = 571.50
  5. Step 5: Solve for x
    x = 571.50/21.79
  6. Step 6: Final answer
    x = 26.23

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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.