# How many robots are needed if 300 chairs have to be built from 2:00 p.m. to 7:00 p.m. by a team of robots if each takes 4 minutes to build one chair?A. 19B. 6C. 5D. 4E. 3

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

The chairs are to be built from 2:00 p.m. to 7:00 p.m. That is a time period of 5 hours or 5*60 = 300 minutes.

The number of chairs to be built is 300. This essentially means that 1 chair should be built in a minute.

As each robot takes 4 minutes to build a chair, 4 robots are required to be able to build 4 chairs in 4 minutes or 1 chair in 1 minute.

The correct answer is option D or 4 robots.

shaznl1 | High School Teacher | (Level 1) Salutatorian

Posted on

First, lets see how much time the robots total took. Since the rate of robots is measured in minutes, lets changed the number of hours into minutes.

7-2 = 5 HOURS= 5*60= 300 minutes

so every robot worked 300 minutes.

Let's see how many chairs can one robot build in 300 minutes

300/4 = 75 chairs

the total robot team built 300 chairs.

Inevitably, there are 300/75 = 4 robots in the team

The final answer to this MC is D (4 robots).

Actually, this could be solved by plugging in method. However, i prefer to use algebra.

givingiswinning | Student, Grade 10 | (Level 1) Valedictorian

Posted on

7 - 2 =5

5 x 60 = 300

300 / 4 = 75

300 / 75 =4

D. 4

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

Posted on

How many robots are needed if 300 chairs have to be built from 2:00 p.m. to 7:00 p.m. by a team of robots if each takes 4 minutes to build one chair?

A. 19
B. 6
C. 5
D. 4
E. 3

7 - 2 =5

they have 5 hours and there are 60 mins in an hour

5 x 60 = 300

so they have 300 minutes to build 300 chairs:

300 / 4 = 75

300 / 75 =4

so the answer is D. 4