Over the top (OTT) subscribers of a platform are segregated into three categories: i) Kid, ii) Elder, and iii) Others. Some of the subscribers used one app and the others used multiple apps to access the platform. The figure below shows the percentage of the total number of subscribers in 2023 and 2024 who belong to the ‘Kid’ and ‘Elder’ categories.

The following additional facts are known about the numbers of subscribers:

1. The total number of subscribers increased by 10% from 2023 to 2024.
2. In 2024, 1/2 of the subscribers from the ‘Kid’ category and 2/3 of the subscribers from the ‘Elder’ category use one app.
3. In 2023, the number of subscribers from the ‘Kid’ category who used multiple apps was the same as the number of subscribers from the ‘Elder’ category who used one app.
4. 10,000 subscribers from the ‘Kid’ category used one app and 15,000 subscribers from the ‘Elder’ category used multiple apps in 2023.

How many subscribers belonged to the ‘Others’ category in 2024?

The correct answer is 55000.

Step 1: Analyze the chart data for 2023 and 2024
By reviewing the bar chart provided in the image:
- In 2023 (represented by the solid black bars):
• The percentage of subscribers in the 'Kid' category is 15%.
• The percentage of subscribers in the 'Elder' category is 20%.
- In 2024 (represented by the horizontal-striped bars):
• The percentage of subscribers in the 'Kid' category is 20%.
• The percentage of subscribers in the 'Elder' category is 30%.

Step 2: Define variables and set up equations for 2023
Let $N_{2023}$ be the total number of subscribers in 2023.
According to the chart:
• Number of subscribers in the 'Kid' category in 2023 = $0.15\times N_{2023}$
• Number of subscribers in the 'Elder' category in 2023 = $0.20\times N_{2023}$

From the given facts about 2023:
1. From Fact 4, 10,000 subscribers from the 'Kid' category used one app, and 15,000 subscribers from the 'Elder' category used multiple apps.
2. Let $x$ be the number of 'Kid' subscribers who used multiple apps. By Fact 3, this is equal to the number of 'Elder' subscribers who used one app.
Therefore:
• Total Kids in 2023 = $\mathrm{10,000}+x$
• Total Elders in 2023 = $x+\mathrm{15,000}$

We can write the following system of equations:
$$0.15N_{2023}=\mathrm{10,000}+x\text{(Equation 1)}$$
$$0.20N_{2023}=\mathrm{15,000}+x\text{(Equation 2)}$$

Subtract Equation 1 from Equation 2:
$$(0.20-0.15)N_{2023}=(\mathrm{15,000}+x)-(\mathrm{10,000}+x)$$
$$0.05N_{2023}=\mathrm{5,000}$$
$$N_{2023}=\frac{\mathrm{5,000}}{0.05}=\mathrm{100,000}$$

Step 3: Calculate the total number of subscribers in 2024
According to Fact 1, the total number of subscribers increased by 10% from 2023 to 2024.
$$N_{2024}=1.10\times N_{2023}=1.10\times \mathrm{100,000}=\mathrm{110,000}$$

Step 4: Calculate the number of subscribers in the 'Others' category in 2024
In 2024, the categories are distributed as follows:
• Kid category = 20%
• Elder category = 30%
• Others category = 100% - 20% - 30% = 50%

Therefore, the number of subscribers who belonged to the 'Others' category in 2024 is:
$${\text{Others}}_{2024}=50\%\text{of}{N}_{2024}=0.50\times \mathrm{110,000}=\mathrm{55,000}$$