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Finding the Fourth Proportional to 900.40, 1,242.80 and 638.48

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Solution

The fourth proportional to 900.40, 1,242.80 and 638.48 is: 881.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    900.40 : 1,242.80 = 638.48 : x
  2. Step 2: Convert to fraction form
    900.40/1,242.80 = 638.48/x
  3. Step 3: Cross multiply
    900.40x = 1,242.80 × 638.48
  4. Step 4: Simplify right side
    900.40x = 793,502.94
  5. Step 5: Solve for x
    x = 793,502.94/900.40
  6. Step 6: Final answer
    x = 881.28

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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.