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SAT - Math - Ratio and Proportion

Wrong Options (more)

Question 6 of SAT Math D113 has wrong options. Where do I report this? 

 

The amount of money a teacher earns is directly proportional to the number of students he teaches. The teacher earns $ 250 when he teaches 4 students. How much will he earn if he teaches 15 students?


Options:

A.

500

B.

1025

C.

1175

D.

1125

 

Solution

earning ex no of students

          ⇨ earning = constant × no. of students

          ⇨ 250 = constant × 4

          ⇨ Constant =  = 75

           So, for 15 students earning = 75 × 15 = $ 1125 

 

For this solution, the teacher should earn $300 and not $250. 

D

A hospital stores one type of medicine in 2-decagram containers (more)

A hospital stores one type of medicine in 2-decagram containers. Based on the information given in the box above, how many 1-milligram doses are there in one 2-decagram container?

1 decagram = 10 gram = 10000 miligram

2 decagram = 20000 miligram

total number of 1 miligram doses = 20000

If a/b=2, what is the value of 4b/a? (more)

If a/b=2, what is the value of 4b/a?

 

a/b = 2

=> b/a = 1/2

4b/a = 4* 1/2 = 2

If y=kx, where k is a constant, and y=24 when x = 6, what is the value of y when x=5? (more)

If y=kx, where k is a constant, and y=24 when x = 6, what is the value of y when x=5?

y = kx

24 = k6

k = 4

 

when x = 5

y = kx = 4*5 = 20

The value of x and y in the table above are related so that (y-1) is directly proportional to (x+1). What is the value of b+a? (more)

x 0 1 2
y 10 a b

The value of x and y in the table above are related so that (y-1) is directly proportional to (x 1). What is the value of b a?

Given (y-1) = k (x+1)

from first column

10-1 = k(0+1)

k = 9

from second column

a -1 = 9*(1+1) = 18

a = 19

from third column

b-1 = 9*(2+1) = 27

b = 28

a + b = 28 + 18 = 46