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Finding the Fourth Proportional to 1,387.68, 1,914.92 and 828.78

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Solution

The fourth proportional to 1,387.68, 1,914.92 and 828.78 is: 1,143.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.68 : 1,914.92 = 828.78 : x
  2. Step 2: Convert to fraction form
    1,387.68/1,914.92 = 828.78/x
  3. Step 3: Cross multiply
    1,387.68x = 1,914.92 × 828.78
  4. Step 4: Simplify right side
    1,387.68x = 1,587,047.40
  5. Step 5: Solve for x
    x = 1,587,047.40/1,387.68
  6. Step 6: Final answer
    x = 1,143.67

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Double scale
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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.