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Question

The following table shows the percentage (%) distribution of students studying in six classes A-F of a school and shows the ratio of boys to girls among them. Number of students studying in all six classes together is 600.

Class-wise distribution of students

Class% Students

Ratio 

Boys ∶ Girls

A20%3 ∶ 2
B12%3 ∶ 1
C16%5 ∶ 3
D15%8 ∶ 7
E21%4 ∶ 3
F16%1 ∶ 1

If P and Q are the differences between the number of boys and girls in class A and class C, respectively, then the percentage of P with reference to Q is

The correct answer is 100%

Analyzing Student Distribution and Ratios

The question provides a table showing the distribution of 600 students across six classes (A to F) and the ratio of boys to girls in each class. We need to calculate the difference between the number of boys and girls in two specific classes, A and C, and then find what percentage the difference in class A (P) is of the difference in class C (Q).

Class % Students Ratio Boys : Girls
A 20% 3 : 2
B 12% 3 : 1
C 16% 5 : 3
D 15% 8 : 7
E 21% 4 : 3
F 16% 1 : 1

Total number of students in the school is 600.

Calculating Students in Class A

First, let's find the total number of students in class A.

  • Percentage of students in Class A = 20%
  • Total students = 600
  • Number of students in Class A = $20\%$ of $600$
  • Number of students in Class A = $\frac{20}{100} \times 600 = 0.20 \times 600 = 120$

Calculating Boys and Girls in Class A

The ratio of boys to girls in Class A is 3 : 2.

  • Total ratio parts = $3 + 2 = 5$
  • Number of boys in Class A = $\frac{\text{Boys ratio part}}{\text{Total ratio parts}} \times \text{Total students in Class A}$
  • Number of boys in Class A = $\frac{3}{5} \times 120 = 3 \times \frac{120}{5} = 3 \times 24 = 72$
  • Number of girls in Class A = $\frac{\text{Girls ratio part}}{\text{Total ratio parts}} \times \text{Total students in Class A}$
  • Number of girls in Class A = $\frac{2}{5} \times 120 = 2 \times \frac{120}{5} = 2 \times 24 = 48$
  • Check: $72 + 48 = 120$ (Total students in Class A)

Calculating Difference P in Class A

P is the difference between the number of boys and girls in class A.

  • P = Number of boys in Class A - Number of girls in Class A
  • P = $72 - 48 = 24$

Calculating Students in Class C

Next, let's find the total number of students in class C.

  • Percentage of students in Class C = 16%
  • Total students = 600
  • Number of students in Class C = $16\%$ of $600$
  • Number of students in Class C = $\frac{16}{100} \times 600 = 0.16 \times 600 = 96$

Calculating Boys and Girls in Class C

The ratio of boys to girls in Class C is 5 : 3.

  • Total ratio parts = $5 + 3 = 8$
  • Number of boys in Class C = $\frac{\text{Boys ratio part}}{\text{Total ratio parts}} \times \text{Total students in Class C}$
  • Number of boys in Class C = $\frac{5}{8} \times 96 = 5 \times \frac{96}{8} = 5 \times 12 = 60$
  • Number of girls in Class C = $\frac{\text{Girls ratio part}}{\text{Total ratio parts}} \times \text{Total students in Class C}$
  • Number of girls in Class C = $\frac{3}{8} \times 96 = 3 \times \frac{96}{8} = 3 \times 12 = 36$
  • Check: $60 + 36 = 96$ (Total students in Class C)

Calculating Difference Q in Class C

Q is the difference between the number of boys and girls in class C.

  • Q = Number of boys in Class C - Number of girls in Class C
  • Q = $60 - 36 = 24$

Calculating Percentage of P with Reference to Q

We need to find the percentage of P with reference to Q. This is calculated as $(\frac{P}{Q} \times 100)$.

  • P = 24
  • Q = 24
  • Percentage = $\frac{P}{Q} \times 100 = \frac{24}{24} \times 100 = 1 \times 100 = 100\%$

The percentage of P with reference to Q is 100%.

Revision Table: Key Calculations Summary

Class % Students Total Students (of 600) Ratio B:G Boys Girls Difference (Boys - Girls)
A 20% 120 3:2 72 48 P = 24
C 16% 96 5:3 60 36 Q = 24

Percentage of P with reference to Q = $(\frac{24}{24}) \times 100 = 100\%$.

Additional Information: Percentage and Ratio Concepts

Understanding percentages and ratios is fundamental for solving problems like this one, often found in data interpretation questions.

  • Percentage: A percentage is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", or the abbreviation "pct.". For example, 20% means 20 out of 100. To find a percentage of a number, you convert the percentage to a decimal (divide by 100) and multiply by the number.
  • Ratio: A ratio compares two quantities of the same kind. It is often written with a colon (:) between the quantities, like 3:2. The parts of the ratio represent proportional divisions of a whole. If the ratio of boys to girls is 3:2, it means that for every 3 boys, there are 2 girls. The total number of parts is 3 + 2 = 5. If there are 120 students, each part represents $120/5 = 24$ students. So, boys = $3 \times 24 = 72$ and girls = $2 \times 24 = 48$.
  • Percentage 'With Reference To': When you calculate the percentage of one value (X) with reference to another value (Y), you are finding what fraction X is of Y and expressing that fraction as a percentage. The formula is $(\frac{X}{Y}) \times 100\%$.

These concepts are widely applicable in various data analysis scenarios, including student demographics, sales figures, and survey results.

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Important Questions from Tabulation

  1. The table shows District-wise data of a number of primary school teachers posted in schools of a city.

    Study the table and answer the question:

    District

    Male teachers

    Female teachers

    East

    1650

    2375

    North

    1075

    2651

    West

    1280

    1520

    South

    1170

    1085

    Central

    690

    859


    What is the difference between the total number of male teachers in the districts East, North, West taken together and the total number of female teachers in the districts East and South?
  2. Table shows income (in Rs. ) received by 4 employees of a company during the month of December 2020 and all their income sources.

    Source

    Amit

    Suresh

    Nitin

    Varun

    Salary

    35000

    38500

    29000

    42000

    Arrears

    6000

    6300

    5000

    7500

    Bonus

    1000

    1100

    1000

    1240

    Overtime

    1800

    1950

    1400

    1500


    What is the ratio of salary of Varun to his income other than salary?
  3. Study the table and answer the question:

    Income (Rs.)

    No. of persons

    Less than 200

    12

    Less than 250

    26

    Less than 300

    34

    Less than 350

    40

    Less than 400

    50


    What is the percentage of persons earning Rs. 250 or more?
  4. The following table shows the annual profit of a company (in Rs. lakh).

    2014-2015

    2015-2016

    2016-0217

    2017-2018

    2018-2019

    625

    690

    725

    775

    815

    The period which has the maximum percentage increase in profit over the previous year is:

  5. The table given below shows the number of persons participating in a survey from 6 different states.

    States Persons 
    S1100
    S2200 
    S3400 
    S4500 
    S5600 
    S6800

    What is the ratio of number of person participating in a survey from state S3 to the number of person participating in a survey from state S4?

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