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Finding the Fourth Proportional to 153.12, 210.72 and 128.76

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Solution

The fourth proportional to 153.12, 210.72 and 128.76 is: 177.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.12 : 210.72 = 128.76 : x
  2. Step 2: Convert to fraction form
    153.12/210.72 = 128.76/x
  3. Step 3: Cross multiply
    153.12x = 210.72 × 128.76
  4. Step 4: Simplify right side
    153.12x = 27,132.31
  5. Step 5: Solve for x
    x = 27,132.31/153.12
  6. Step 6: Final answer
    x = 177.20

Related Problems

Find fourth proportional to 76.56, 105.36 and 64.38
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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.