Question

a random sample of students was surveyed and asked to list their grade level and whether or not they have a pet.

• 21 seventh graders said they have pets.
• 45 seventh graders were surveyed.
• 56 eighth graders were surveyed.
• 48 total students said they have pets.

fill in the missing values in the table below.
pets survey
7th grade
8th grade
total
pets
no pets
total

Explanation:

Step1: Fill in 7th grade row

• Pets column: Given 21 seventh - graders have pets.
• Total column: Given 45 seventh - graders were surveyed.
• No Pets column: Use the formula \(No\ Pets = Total - Pets\). So \(45−21 = 24\).

Step2: Fill in 8th grade row

• Pets column: Use the formula \(8th\ grade\ Pets=Total\ Pets - 7th\ grade\ Pets\). Given total pets \(48\) and 7th grade pets \(21\), so \(48−21=27\).
• Total column: Given 56 eighth - graders were surveyed.
• No Pets column: Use the formula \(No\ Pets = Total - Pets\). So \(56 - 27=29\).

Step3: Fill in Total row

• Pets column: Given \(48\).
• No Pets column: Use the formula \(No\ Pets=7th\ grade\ No\ Pets + 8th\ grade\ No\ Pets\). So \(24 + 29=53\).
• Total column: Use the formula \(Total = 7th\ grade\ Total+8th\ grade\ Total\). So \(45 + 56 = 101\).

Answer:

	Pets	No Pets	Total
8th grade	27	29	56
Total	48	53	101