Question

A student can solve 20 problems in 30 minutes. How long would it take him to solve 50 problems? (Assume that the student works at the same pace).

Answer 1

Explanation:

Answer 2

Student takes 75 minutes to solve 50 problems.

SOLUTION:

Given that, a student can solve 20 problems in 30 minutes.

We have to find the time to solve 50 problems. (Assume that the student works at the same pace).

Now, we know that,

`\Rightarrow 20 \text { problems } \rightarrow 30 \text { minutes } \\\\ \text{Then, } 50 \text { problems } \rightarrow \text { (let it be) n minutes. }`

So, by cross multiplication method,

`\Rightarrow n * 20=30 * 50 \rightarrow 2 * n=30 * 5 \rightarrow 2 n=150 \rightarrow n=75`

Cross multiplications steps: (To find Single Variable)

Step 1: Multiply the numerator of the left-hand fraction by the denominator of the right-hand fraction.

Step 2: Multiply the numerator of the right-hand fraction by the denominator of the left-hand fraction.

Step 3: Set the two products equal to each other.

Step 4: Solve for the variable.