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Finding the Fourth Proportional to 1,287.90, 1,777.55 and 790.76

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Solution

The fourth proportional to 1,287.90, 1,777.55 and 790.76 is: 1,091.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.90 : 1,777.55 = 790.76 : x
  2. Step 2: Convert to fraction form
    1,287.90/1,777.55 = 790.76/x
  3. Step 3: Cross multiply
    1,287.90x = 1,777.55 × 790.76
  4. Step 4: Simplify right side
    1,287.90x = 1,405,615.93
  5. Step 5: Solve for x
    x = 1,405,615.93/1,287.90
  6. Step 6: Final answer
    x = 1,091.40

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Half scale
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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.