Mark M. answered • 03/08/15
Tutor
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(278)
Mathematics Teacher - NCLB Highly Qualified
And wonderment exists that students hate word problems!
First:
acid = x
water = x
Second
acid = x - 20
water = x + 20
Third
acid = (x - 20) + (2/3)(x + 20)
water = (1/3)(x + 20)
Fourth
acid = 4 water
(x - 20) + (2/3)(x + 20) = 4(1/3)(x + 20)
x - 20 + 2x/3 + 40/3 = 4x/3 + 80/3
x - 20 = 2x/3 + 40/3
x/3 = 100/3
x = 100
Mark M.
By what method did you get "40?"
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03/10/15
Amey B.
hello sir in my book there is answer like this
4[1/3(x+20)]=x+2/3(x+20)
is this correct or wrong pls reply me
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03/18/15
Mark M.
If 2/3 of the water tube is poured into the acid tube, only 1/3 remains in the water tube.
From what I can see of your text book, it is in error.
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03/18/15
Amey B.
thank u
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03/21/15
Mark M.
You are welcome.
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03/21/15
Amey B.
i have another question
4/7 of birthday cake was eaten on your birthday. The next day dad ate 1/2 of what was left. You get to finish the cake how much is left
in my book
let x be cake
x-4x/7 =3x/7
now 3x/7*1/2
answer come 3/14
my confusion is
4/7 of cake means 4/7 is part of cake so we took 4x/7
now when dad ate 1/2 part of remaining cake so it should be like this 3x/7*x/2 why i take x/2 because it is part of cake like previously but when i trying to solve this answer come 3x^2/14.
So for only first sentence why we took 4x/7 and second sentence took 1/2.
therefore how we know when to use x
please sent me detail information
4/7 of birthday cake was eaten on your birthday. The next day dad ate 1/2 of what was left. You get to finish the cake how much is left
in my book
let x be cake
x-4x/7 =3x/7
now 3x/7*1/2
answer come 3/14
my confusion is
4/7 of cake means 4/7 is part of cake so we took 4x/7
now when dad ate 1/2 part of remaining cake so it should be like this 3x/7*x/2 why i take x/2 because it is part of cake like previously but when i trying to solve this answer come 3x^2/14.
So for only first sentence why we took 4x/7 and second sentence took 1/2.
therefore how we know when to use x
please sent me detail information
Report
04/03/15
Mark M.
Typical of word problems,this one give you information in one direction - what was eaten, and asks the question in the opposite - what was left. This is one example where trying to set up an equation (using a variable) can cause more trouble than it is
worth.
Like the book, start with 1 cake.
4/7 is eaten. That leaves 3/7.
Your dad leaves for you 1/2 of that, (1/2)(3/7) - 3/14.
Report
04/03/15
Amey B.
example 1
Two vessels contain mixture of milk and water in ratio 5:2 and 3:1 respectively the ratio of milk and in new solution. If two mixtures are mixed
let there is x milk and water
5x/7+3x/1=41/28
2x/7+x/4=15/28
milk 41 and water 15
example 2
A and B contain milk and water in the ratio 7:3 and 3:2 respectively find the ratio in which the quantity be taken from the vessels so that the ratio of milk and water in water new mixture is 2:1 equal amount
m=milk and w=water
(7/10)m + (3/5)m milk : (3/10)w + (2/5)w water
(7/10)m + (6/10)m 2
----------------- = ---
----------------- = ---
(3/10)w + (4/10)w 1
13m/10 / 7w/10=2/1
13m/7w=2/1
it goes wrong
i did what second problem did i did gather milk with milk and water with water so what is my mistake
• My doubt is in these two example we add milk to milk and water to water. is this rule that we only can add same quantity if it is then why first problem get wrong
• Why we cant add one vessel milk and water to other vessel milk and water
13m/7w=2/1
it goes wrong
i did what second problem did i did gather milk with milk and water with water so what is my mistake
• My doubt is in these two example we add milk to milk and water to water. is this rule that we only can add same quantity if it is then why first problem get wrong
• Why we cant add one vessel milk and water to other vessel milk and water
Report
06/15/15
Amey B.
03/10/15