Home / 158.09-218.21-99.90

Finding the Fourth Proportional to 158.09, 218.21 and 99.90

Calculator

Solution

The fourth proportional to 158.09, 218.21 and 99.90 is: 137.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    158.09 : 218.21 = 99.90 : x
  2. Step 2: Convert to fraction form
    158.09/218.21 = 99.90/x
  3. Step 3: Cross multiply
    158.09x = 218.21 × 99.90
  4. Step 4: Simplify right side
    158.09x = 21,798.68
  5. Step 5: Solve for x
    x = 21,798.68/158.09
  6. Step 6: Final answer
    x = 137.89

Related Problems

Find fourth proportional to 79.04, 109.10 and 49.95
Half scale
Find fourth proportional to 316.17, 436.41 and 199.80
Double scale
Find fourth proportional to 159.09, 219.59 and 100.90
Similar ratio
Find fourth proportional to 237.13, 327.31 and 149.85
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.