Question

In Mrs. Hu’s classroom, 4/5 of the students have a dog as a pet. Of the students who have a dog as a pet, 2/3 have a cat as a pet. If there are 45 students in her class, how many have both a dog and a cat as pets?

Answer 1

2/3 of the 4/5 of the class has a dog and a cat. Just multiply
(2/3)(4/5)=8/15
45*(8/15)=24

Answer 2

Answer:

21 students have both a dog and a cat as pets.

Step-by-step explanation:

Total students in the class = 45

Fraction of students having dog as a pet = $\frac{4}{5}$

Number of students having dos as  a pet ,D= $\frac{4}{5}\times 45=36$

Fraction of students having dog as a cat as a pet= $\frac{2}{3}$

Number of students having dos as a pet ,C= $\frac{2}{3}\times 45=30$

Students having both cat and dog as a pet = D∪C

D∪C  = 45

D∪C = D + C - D∩C

45 = 36+ 30 - D∩C

D∩C = 66 - 45 = 21

21 students have both a dog and a cat as pets.