Home / 660.74-990.40-429.80

Finding the Fourth Proportional to 660.74, 990.40 and 429.80

Calculator

Solution

The fourth proportional to 660.74, 990.40 and 429.80 is: 644.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.74 : 990.40 = 429.80 : x
  2. Step 2: Convert to fraction form
    660.74/990.40 = 429.80/x
  3. Step 3: Cross multiply
    660.74x = 990.40 × 429.80
  4. Step 4: Simplify right side
    660.74x = 425,666.82
  5. Step 5: Solve for x
    x = 425,666.82/660.74
  6. Step 6: Final answer
    x = 644.23

Related Problems

Find fourth proportional to 330.37, 495.20 and 214.90
Half scale
Find fourth proportional to 1,321.48, 1,980.79 and 859.59
Double scale
Find fourth proportional to 661.74, 991.89 and 430.80
Similar ratio
Find fourth proportional to 991.11, 1,485.59 and 644.69
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.