Home / 639.30-990.51

Finding the Third Proportional to 639.30 and 990.51

Calculator

Solution

The third proportional to 639.30 and 990.51 is: 1,534.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.30 : 990.51 = 990.51 : x
  2. Step 2: Convert to fraction form
    639.30/990.51 = 990.51/x
  3. Step 3: Cross multiply
    639.30x = 990.51 × 990.51
  4. Step 4: Simplify right side
    639.30x = 981,109.60
  5. Step 5: Solve for x
    x = 981,109.60/639.30
  6. Step 6: Final answer
    x = 1,534.67

Related Problems

Find third proportional to 319.65 and 495.25
Half scale
Find third proportional to 1,278.60 and 1,981.02
Double scale
Find third proportional to 641 and 994
Similar ratio
Find third proportional to 958.95 and 1,485.76
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.