How to make npc give random different question?

[hadiesyafiq 7]

if (!quest_random) {
				mes "[Swordman Guildsman]";
				mes("Last Question.");
				mes("If.....");
				next();
			}
			switch(quest_random) {
				case 1:
					mes "[Swordman Guildsman]";
					mes("1+3+5 = ???");
					next();
					input(.@guess);
					if (.@guess == 9) {
						mes "[Swordman Guildsman]";
						mes "Then I'll end your training process and send you to the Swordman Guild.";
						callfunc "F_NvErase",1;
						close2;
						savepoint "izlude",128,98; // Old coordinates: (95,104)
						warp "izlude_in",74,167;
						close();
					} else {
						mes("[Swordman Guildsman]");
						mes("Sorry.");
						close();
					}
				case 2:
					mes "[Swordman Guildsman]";
					mes("5+9+5 = ???");
					next();
					input(.@guess);
					if (.@guess == 19) {
						mes "[Swordman Guildsman]";
						mes "Then I'll end your training process and send you to the Swordman Guild.";
						callfunc "F_NvErase",1;
						close2;
						savepoint "izlude",128,98; // Old coordinates: (95,104)
						warp "izlude_in",74,167;
						close();
					} else {
						mes("[Swordman Guildsman");
						mes("Sorry.");
						close();
				}
			}
		}
	}
}

is this right way to make npc ask random different kind of questions?

not only 1 questions but many

Edited November 17, 2020 by hadiesyafiq

[fiction 14]

you can always use something like switch (rand(4))