The student went wrong in step three. the solutions should have been -3 and 5
20 minutes
Because-
If he did ten more minutes then friday just do 30 - 10 whih 20 mins
Number of weekend minutes used: x
Number of weekday minutes used: y
This month Nick was billed for 643 minutes:
(1) x+y=643
The charge for these minutes was $35.44
Telephone company charges $0.04 per minute for weekend calls (x)
and $0.08 per minute for calls made on weekdays (y)
(2) 0.04x+0.08y=35.44
We have a system of 2 equations and 2 unkowns:
(1) x+y=643
(2) 0.04x+0.08y=35.44
Using the method of substitution
Isolating x from the first equation:
(1) x+y-y=643-y
(3) x=643-y
Replacing x by 643-y in the second equation
(2) 0.04x+0.08y=35.44
0.04(643-y)+0.08y=35.44
25.72-0.04y+0.08y=35.44
0.04y+25.72=35.44
Solving for y:
0.04y+25.72-25.72=35.44-25.72
0.04y=9.72
Dividing both sides of the equation by 0.04:
0.04y/0.04=9.72/0.04
y=243
Replacing y by 243 in the equation (3)
(3) x=643-y
x=643-243
x=400
Answers:
The number of weekends minutes used was 400
The number of weekdays minutes used was 243
Answer:
They are both correct
Step-by-step explanation:
It's interpretation of the concept. In common practice multiplying by 10 means you add a zero and that's what we teach 10 year olds. But what does adding a zero mean? It means adding a place value and that's what you learn when you are
So in both examples just add a decimal:
2.0 x 10 = 20.
0.2 x 10 = 2.0
In conclusion, it depends on the level of precision required in the discussion and the level of maturity as to who is correct in their examples. If you are teaching 3rd graders math, by all means you add a zero. If you are discussing physics you are shifting over a place value.
