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Finding the Fourth Proportional to 90, 123.28 and 81.36

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Solution

The fourth proportional to 90, 123.28 and 81.36 is: 111.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    90 : 123.28 = 81.36 : x
  2. Step 2: Convert to fraction form
    90/123.28 = 81.36/x
  3. Step 3: Cross multiply
    90x = 123.28 × 81.36
  4. Step 4: Simplify right side
    90x = 10,030.06
  5. Step 5: Solve for x
    x = 10,030.06/90
  6. Step 6: Final answer
    x = 111.45

Related Problems

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.