Question

The specific brain mass is the brain mass divided by the body mass.Mammal A has twice the body mass of mammal B. What is the ratio of mammal A's specific brain mass to mammal B's? Report your answer using two significant figures.

Answer 1

The expression for the specific brain mass for a mammal is М, br sp,brain M body The relation between the brain mass and body mass of a mammal is, 0.7 М, - (М,) body br The expression for the specific brain mass for the mammal-A is, (A)br м. (A)sp, brain (A)body The expression for the specific brain mass for the mammal-B is (B)br M (B)sp,brain (в)body The ratio of the specific brain mass of the mammal-A to the specific brain mass of the mammal-B is, (A)br (A)body (A) sp,brain (B)sp,brain (B)br (B)body (B)body (A)br M (A)body (B)br Then the relation between the brain mass and body mass of the mammal-A is, 0.7 Мar - (Мде (A)br (A)body

Then the relation between the brain mass and body mass of the mammal-B is, 0.7 Мgы - (Моe) (B)br (B)body Then the ratio of the specific brain mass of the mammal-A to the specific brain mass of the mammal-B is (A) sp.brain M (A)br (B)body M (A)body (B)sp,brain (B)br 0.7 (M (A)body (В)body 0.7 (MB (A)body | (вbody .))|(1. -(M (M 1-0.7 0.7-1 (A)body (Вbody -0.3 0.3 (A)body (B)body The body mass of the mammal-A is twice the body mass of the mammal-B 2M (B)body (АJbody Then calculate the ratio of the specific brain mass of the mammal-A to the specific brain mass of the mammal-B as follows: (MNe) -0.3 (M6 0.3 (A)sp.brain (A)body (Вbody (B)sp,brain )" (Морыя)" 0.3 -(2 -0.3 M рoб (B)body (В)body -(22)(Mj(M -0.3 0.3 -0.3 (B)body (В'body 1 20.3 (A)sp,brain = 0.81225 (B)sp.brain

Therefore, the ratio of the specific brain mass of the mammal-A to the specific brain mass of the mammal-B in two significant figures is 0.81