The bar shows the total number of students in four schools and it also shows the difference between boys and girls in these schools.

If boys in D increase by 25% and girls decreased by 50%, then find the new number of total students in D.

The correct answer is 47.


Step 1: Extract data for School D from the given bar graph.
From the bar graph, we observe the following values for School D:
Blue bar (representing Total Students, i.e., Boys + Girls) = 52
Orange bar (representing Difference between Boys and Girls, i.e., Boys - Girls) = 4

So, we have the following two equations:

$\text{Boys}+\text{Girls}=52$

$\text{Boys}-\text{Girls}=4$

Step 2: Calculate the initial number of Boys and Girls in School D.
Adding both equations together to eliminate Girls:

$2\times \text{Boys}=52+4=56$

$\text{Boys}=\frac{56}{2}=28$

Subtracting the second equation from the first equation to eliminate Boys:

$2\times \text{Girls}=52-4=48$

$\text{Girls}=\frac{48}{2}=24$

Step 3: Calculate the new number of Boys and Girls after the percentage changes.
The number of boys increases by 25%:

$\text{Increase in Boys}=25\%\text{of}28=0.25\times 28=7$

$\text{New number of Boys}=28+7=35$

The number of girls decreases by 50%:

$\text{Decrease in Girls}=50\%\text{of}24=0.50\times 24=12$

$\text{New number of Girls}=24-12=12$

Step 4: Find the new total number of students in School D.

$\text{New Total Students}=\text{New Boys}+\text{New Girls}$

$\text{New Total Students}=35+12=47$

Therefore, the new total number of students in School D is 47.