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Finding the Fourth Proportional to 521.72, 719.90 and 311.90

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Solution

The fourth proportional to 521.72, 719.90 and 311.90 is: 430.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.72 : 719.90 = 311.90 : x
  2. Step 2: Convert to fraction form
    521.72/719.90 = 311.90/x
  3. Step 3: Cross multiply
    521.72x = 719.90 × 311.90
  4. Step 4: Simplify right side
    521.72x = 224,536.81
  5. Step 5: Solve for x
    x = 224,536.81/521.72
  6. Step 6: Final answer
    x = 430.38

Related Problems

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Double scale
Find fourth proportional to 522.72, 721.28 and 312.90
Similar ratio
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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.