SBI-Ratio Guided Practice

Question 1

Given sum of two parts and the ratio between two parts.

How to find the quantity of the parts?

Answer 1

Step 1: Ratio = Quantity_A /Quantity_B

so Quantity_A = Ratio*Quantity_B

Step 2: since Quantity_A+ Quantity_B = Total(the sum given)

so Quantity_A + Ratio*Quantity_B = Total

solve this equation, we can get Quantity_A,then Quantity_B

So the idea is: using one of the facts to represent of quantity using another quantity, then using another fact to get solution

Question 2

A bag contains 60 marbles, some blue and some green. The ratio of blue marbles to green ones is 1 : 5. How many blue marbles are there?

Answer 2

Green = #Blue/Ratio

Fact #1: #Blue + #Green = 60. Fact #2: #Blue/#Green = 1/5

Step 1:Use Fact#1 to represent #Green using #Blue:

Step 2: Use Fact#2 to solve:

Step 3: Check

Question 3

Ray want to divide his $320 money into two piece according to the ratio 3 : 5. He will give donate the smaller part to charity and keep the larger part to buy a computer. How much will he donate to charity?

Answer 3

Fact #1:____________. Fact#2:______________

Step 1:__________________________________

Step 2:__________________________________

Step 3:__________________________________

Question 4

A jar contains 34 marbles, of which 5 are blue, 17 are red, and the rest are green. What is the ratio of blue marbles to green marbles?

Question 5

There are 30 children in Ms. Robinson’s class. The ratio of the number of boys to the number of children in Ms. Robinson’s class is 3:5. How many boys are in the class? How many girls are in the class?

Question 6

Janet only listens to rock and hip-hop music on her iPhone. Altogether she has 400 MP3s on her iPhone. The ratio of the number of her hip-hop songs to the number of her rock songs is 3:5. How many hip-hop songs does she have?

Question 7

Will only owns Nike and Under Armour shirts. The ratio of Will’s Nike shirts to his Under Armour shirts is 4:11. If Will has 30 shirts total, how many of them are Nike?

Question 8

At Rosa Parks High School, all of the students either ride the bus or walk to school. On Tuesday, the ratio of the number of students who rode the bus to school to the number of students who walked to school was 12:15. On Friday, the ratio of the number of students who rode the bus to school to the number of students who walked to school was 3:9. There was a thunderstorm on Tuesday and the sun was shining on Friday. If 328 students rode the bus to school on Tuesday, how many students walked to school on Tuesday?

Question 9

Monica has 3 red roses in her bouquet for every 5 yellow roses. The bouquet has two dozen red and yellow roses. How many are red roses? Use a ratio to solve the problem.

Question 10

There are 28 employees at the local bank. Every morning, 5 out of 7 employees use Route A to drive to work. How many employees use Route A to drive to work?

Question 11

At Washington School, they keep track of all the books students read. For every 9 seventh- graders in the school, 5 claim that Harry Potter is their favorite book. Washington School has 90 seventh-graders; how many seventh-graders prefer Harry Potter?