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Finding the Fourth Proportional to 1,389.36, 1,917.70 and 830.21

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Solution

The fourth proportional to 1,389.36, 1,917.70 and 830.21 is: 1,145.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.36 : 1,917.70 = 830.21 : x
  2. Step 2: Convert to fraction form
    1,389.36/1,917.70 = 830.21/x
  3. Step 3: Cross multiply
    1,389.36x = 1,917.70 × 830.21
  4. Step 4: Simplify right side
    1,389.36x = 1,592,093.72
  5. Step 5: Solve for x
    x = 1,592,093.72/1,389.36
  6. Step 6: Final answer
    x = 1,145.92

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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.