math
posted by rebeca .
alter working 4 hours, frank has made 21 machine parts.at the same rate how many parts can he make in 7 hours? 4(21)/7,7(21),7(21)/4,7(4)/21,7(4)(21)?

Please post your answer and we'll be glad to check it.

i choose a)4(21)/7

Look at dimensional analysis.
21 parts/4 hrs x ?hrs = ?parts. 
How can a) be the right answer? 4(21)/7 = 12. The problem has stated that he made 21 parts in 4 hours. How can he make fewer parts in more hours?
Please try again.
Hint: you could set up a proportion:
4 is to 21 as 7 is to x 
d)7(4)/21

7(4)/21.
Do the math. Does the answer make sense?
Respond to this Question
Similar Questions

math
A machine has four components, A, B, C, and D, set up in such a manner that all four parts must work for the machine to work properly. Assume the probability of one part working does not depend on the functionality of any of the other … 
Algebra
find the unit rate for number of parts manufactured per hour if 1630 parts are made in 6 hours. round to the nearest integer. SHOW ALL WORK. 
math
After working 4 hours, Frank has made 21 machine parts. At the same rate, how many parts can he make in 7 hours? 
math
After working 4 hours frank made 21 machine parts. it's the same rate how many parts can he make in 7 hours 
Math
Find a unit rate for number of parts manufactured per hour if 1628 parts are made in seven hours round to the nearest integer 
Mathematics
A machine takes 4.2 hours to make 7 parts. At that rate, how many parts can the machine make in 28.8 hours 48 parts 41 parts 172 parts 17 parts 
Math
Please help! It says A machine takes 4.0 hours to make 8 parts. At that rate, how many parts can the machine make in 31.0 hours? 
Math
Jocelyn made a spinner If Jocelyn spins only one time what is the probability that the arrow will not land on a red section of the spinner? 
math
A worker in an assembly line take 2 hours to produce 120 parts. At that rate how many parts can she produce in 9 hours. can somebody tell me if this the right answer yes or no, 120/2=60 60*9= 540 
Quantitative, stastics and business
A company has three machines A, B and C which all produce the same two parts, X and Y. of all the parts produced, machine A produces 60%, machine B produces 30%, and machine C produces the rest. 40% of the parts made by machine A are …