Question

one teacher noticed there were twice as many students with brown hair as black hair. which choice below show

option 1:

hair color	blond	black	brown
number of students	20	10	5

option 2:

hair color	blond	black	brown
number of students	10	10	5

option 3:

hair color	blond	black	brown
number of students	20	10	20

option 4:

hair color	blond	black	brown
number of students	10	5	20

(top buttons: show formula page, show calculator)

Explanation:

Step1: Analyze the condition

The condition is that the number of students with brown hair is twice the number of students with black hair. Let the number of black - haired students be \(x\), then the number of brown - haired students should be \(2x\).

Step2: Check each option

• Option 1: Number of black - haired students \(x = 10\), number of brown - haired students \(y=5\). \(2x=2\times10 = 20

eq5\), so this option is wrong.

• Option 2: Number of black - haired students \(x = 10\), number of brown - haired students \(y = 5\). \(2x=2\times10=20

eq5\), so this option is wrong.

• Option 3: Number of black - haired students \(x = 10\), number of brown - haired students \(y = 20\). \(2x=2\times10 = 20\), which satisfies the condition \(y = 2x\).
• Option 4: Number of black - haired students \(x = 5\), number of brown - haired students \(y = 20\). \(2x=2\times5=10

eq20\), so this option is wrong.

Answer:

The correct option is the third one (the table with blond: 20, black: 10, brown: 20), that is:

Hair color	blond	black	brown