Home / 990.90-1,485.90-405.87

Finding the Fourth Proportional to 990.90, 1,485.90 and 405.87

Calculator

Solution

The fourth proportional to 990.90, 1,485.90 and 405.87 is: 608.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.90 : 1,485.90 = 405.87 : x
  2. Step 2: Convert to fraction form
    990.90/1,485.90 = 405.87/x
  3. Step 3: Cross multiply
    990.90x = 1,485.90 × 405.87
  4. Step 4: Simplify right side
    990.90x = 603,082.23
  5. Step 5: Solve for x
    x = 603,082.23/990.90
  6. Step 6: Final answer
    x = 608.62

Related Problems

Find fourth proportional to 495.45, 742.95 and 202.94
Half scale
Find fourth proportional to 1,981.80, 2,971.80 and 811.74
Double scale
Find fourth proportional to 991.90, 1,487.40 and 406.87
Similar ratio
Find fourth proportional to 1,486.35, 2,228.85 and 608.81
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.