鞋号 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
人数 | 2 | 4 | 6 | 9 | 7 | 2 | 2 |
(1)从这个班中任选一个同学,鞋号是19号的可能性是.
(2)从这个班中任选一个同学,他的鞋号为21号或22号的可能性与比较,正确的是 .
(①大于 ②小于 ③等于)
同类型试题
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2