Short Answer: 18 minutes
Remark
The answer to this problem is less than the smallest time of the two people working together. that fact lets out C and D (38 minutes and 75 minutes). Now you have to choose 15 minutes and 18 minutes. There's a method. No guessing needed.
Givens
Let the time for Sophie = S
Let the time for Simon = M
Let the job to completion = 1
S = 45 minutes
M = 30 minutes
Step One
Convert minutes to hours.
45 minutes = 45 / 60 = 3/4 hour = 0.75 hour
30 minutes = 30 / 60 = 1/2 hour = 0.50 hour
Step Two
Set up the Equation
The formula is a form of job / hour.
Let the time = t that they both have to work
job = 1 in these problems.
1/S + 1/M = 1/t
1/0.75 + 1/0.5 = 1/t
Solve
1 ÷ 0.75 = 1.33333
1 ÷ 0.5 = 2
1.3333 + 2 = 3.33333
3.3333 = 1 / t Multlply both sides by t
3.3333*t = 1
t = 1 / 3.333333333
t = 0.3 of an hour
1 hour = 60 minutes
0.3 hours = x Cross Multiply
x = 60 * 0.3
x = 18 minutes
Answer working together it took them 18 minutes <<<<<
The group lose 8.8 pounds per day. For a detailed calculation, please refer to the attachment.
That means that the first rectangle and the first triangle ave athe same perimiter
so therefor
perimiter=sides added up
rectangle has 4 sides bu 2 is given so double it since the other side is same legnth
rec=x+x+4
multiply 2
2x+2x+8=4x+8=perimiter
this is equal to perimiter of triangle which is
x+9+x+5+x=3x+14
therefor
4x+8=3x+14
subtract 3x from both sides
x+8=14
subtract 8 from both sides
x=6
first one x=6
second rectangle and second triangle
s+7 and 3s
2 sides
2s+14+6s=p
8s+14=p
traignel=2s+12+2s+12+2s+12=6s+36=p
they are equal so
8s+14=6s+36
subtract 6s from both sides
2s+14=36
subtract 14 from both sides
2s=22
divide both sideds by 2
s=11
the values are
pair one:
x=6
pair 2:
s=11
