Solution By Steps

Step 1: Mean Height Hypothesis

For the mean height of Grade 12 students being less than 66 inches:

This is a one-tailed test because it specifies a direction (less than).

Step 2: Standard Deviation Hypothesis

For the standard deviation of height not being equal to 5 inches:

This is a two-tailed test because it does not specify a direction (not equal to).

Step 3: Height Difference Hypothesis

For the average height difference between male Grade 7 and Grade 12 students:

This is a two-tailed test as it does not specify a direction (differ).

Step 4: Proportion Hypothesis

For the proportion of senior male students’ height being significantly higher than senior female students:

This is a one-tailed test because it specifies a direction (higher than).

Step 5: Average Grade Hypothesis

For the average grade of Grade 11 students in Statistics being lower than their average grade in Calculus:

This is a one-tailed test because it specifies a direction (lower than).

Step 6: Vaccine Hypothesis

For the vaccine reducing the risks of viral infections:

This is a one-tailed test because it specifies a direction (reduces).

Step 7: Enrolment Hypothesis

For the enrolment in elementary schools not being the same as secondary schools:

This is a two-tailed test as it does not specify a direction (not the same as).

Step 8: IQ Level Hypothesis

For male adolescents having higher intelligence quotient level than female adolescents:

This is a one-tailed test because it specifies a direction (higher than).

Step 9: Internet Users Hypothesis

For the average number of internet users this year being significantly higher than last year:

This is a one-tailed test because it specifies a direction (higher than).

Step 10: Medication Rate Hypothesis

For Paracetamol and Ibuprofen having the same rate of time to reduce headaches:

This is a two-tailed test as it does not specify a direction (same rate).

Final Answer

One-tailed test

Two-tailed test

Two-tailed test

One-tailed test

One-tailed test

One-tailed test

Two-tailed test

One-tailed test

One-tailed test

Two-tailed test

Key Concept

Directionality in Hypothesis Testing

Key Concept Explanation

Hypothesis tests can be one-tailed (specifying a direction) or two-tailed (not specifying a direction). One-tailed tests are used when the hypothesis specifies a direction of the effect, while two-tailed tests are used when the hypothesis does not specify a direction. Understanding the directionality is crucial in determining the appropriate statistical test to use for a given hypothesis.