In a certain class, about 4 out of every 5 students are left handed. If there are 40 students in the class, how many students are left handed?

Introduction / Context:
This question tests basic percentage and ratio understanding in the context of a simple real life situation. The statement says that about 4 out of every 5 students are left handed and asks you to apply that ratio to a total of 40 students. Problems like this are very common in aptitude tests to check comfort with fractions, ratios and proportional reasoning.

Given Data / Assumptions:

• In the class, 4 out of every 5 students are left handed.
• Total number of students in the class = 40.
• The ratio 4 : 5 applies uniformly across the whole class.
• We assume every student is either left handed or right handed, with no other category needed for the calculation.

Concept / Approach:
The phrase 4 out of 5 means that the fraction of left handed students is 4/5 of the entire group. To find how many students this represents in a class of 40, we multiply the total number of students by this fraction. This is the same as finding 80 percent of 40, since 4/5 is equal to 0.8 or 80 percent.

Step-by-Step Solution:
Ratio of left handed students = 4 out of 5 = 4/5. Total number of students in the class = 40. Number of left handed students = (4/5) * 40. Compute: (4/5) * 40 = 4 * (40/5) = 4 * 8 = 32. So there are 32 left handed students in the class.

Verification / Alternative check:
Another way is to first find how many students correspond to one part in the ratio 4 : 5. Each group of 5 students contains 4 left handed students. With 40 students, the number of groups of 5 is 40 / 5 = 8. Each group contributes 4 left handed students, so total left handed students = 8 * 4 = 32. This confirms the previous calculation.

Why Other Options Are Wrong:

• 30: This corresponds to 30/40 = 3/4 = 75 percent, not 4/5.
• 28: This is 28/40 = 7/10 = 70 percent, again not equal to 4/5.
• 34 and 36: These are even larger proportions, more than the given 4 out of 5 ratio.

Common Pitfalls:
Learners sometimes mistakenly divide 40 by 4 instead of multiplying by 4/5, or they misread 4 out of 5 as 4 percent. Always convert the phrase into a clear fraction or percentage before computing. Writing the fraction 4/5 beside the total and then multiplying makes the process much easier to follow.

Final Answer:
The number of left handed students in the class is 32.