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Finding the Fourth Proportional to 65.40, 90.16 and 40.80

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Solution

The fourth proportional to 65.40, 90.16 and 40.80 is: 56.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.40 : 90.16 = 40.80 : x
  2. Step 2: Convert to fraction form
    65.40/90.16 = 40.80/x
  3. Step 3: Cross multiply
    65.40x = 90.16 × 40.80
  4. Step 4: Simplify right side
    65.40x = 3,678.53
  5. Step 5: Solve for x
    x = 3,678.53/65.40
  6. Step 6: Final answer
    x = 56.25

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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.