Home / 661.20-990-372.12

Finding the Fourth Proportional to 661.20, 990 and 372.12

Calculator

Solution

The fourth proportional to 661.20, 990 and 372.12 is: 557.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.20 : 990 = 372.12 : x
  2. Step 2: Convert to fraction form
    661.20/990 = 372.12/x
  3. Step 3: Cross multiply
    661.20x = 990 × 372.12
  4. Step 4: Simplify right side
    661.20x = 368,398.80
  5. Step 5: Solve for x
    x = 368,398.80/661.20
  6. Step 6: Final answer
    x = 557.17

Related Problems

Find fourth proportional to 330.60, 495 and 186.06
Half scale
Find fourth proportional to 1,322.40, 1,980 and 744.24
Double scale
Find fourth proportional to 662.20, 991.50 and 373.12
Similar ratio
Find fourth proportional to 991.80, 1,485 and 558.18
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.