Calculate the median percentage for male social media users.

Since there are 6 values (an even number), the median is the average of the two middle values (the 3rd and 4th values).

The median percentage for male social media users is $\boxed{52.5\%}$.

3.1.2

This can be determined by comparing the percentages of male and female users for each platform. If the percentage of male users is higher than female users, then the number of female users is fewer than male users.

• Facebook: Male 57%, Female 43% (Female < Male) - Yes
• Instagram: Male 51%, Female 49% (Female < Male) - Yes
• Snapchat: Male 46%, Female 54% (Female > Male) - No
• X/Twitter: Male 56%, Female 44% (Female < Male) - Yes
• TikTok: Male 43%, Female 57% (Female > Male) - No
• YouTube: Male 54%, Female 46% (Female < Male) - Yes

There are 4 such platforms (Facebook, Instagram, X/Twitter, YouTube).

The probability is $\boxed{0.667}$.

3.1.3 (a)

Female users = 405 million
Percentage of female users = 54%

Let $T$ be the total number of users.

The total number of Snapchat users is $\boxed{750 \text{ million}}$.

3.1.3 (b)

Total Snapchat users = 750 million (from 3.1.3 a)
Female Snapchat users = 405 million

Fezeka stated the difference was 61 300 000, which is 61.3 million.
Our calculated difference is 60 million.
Since $60 \text{ million} \neq 61.3 \text{ million}$, Fezeka's statement is INVALID.

The statement is $\boxed{\text{INVALID}}$.