Find the total cost if they will purchase the same type of 15 notebooks and 12 pens.
Answers
Answer:
Deepak bought three notebooks and two pens for Rs 80. His friend
Ram said that the price of each notebook could be Rs 25. Then three notebooks
would cost Rs 75,the two pens would cost Rs 5 and each pen could be forRs2.50.
Another friend Ajay felt that Rs 2.50 for one pen was too little. It would be at least
Rs16. Then the price of each notebook would also be Rs 16.
Rohit also bought the same type of notebooks and pens as Aditya. He paid 110 for 4
notebooks and 3 pens. Later, Deepak guess the cost of one pen is rupees 10 and Rohitguess
the cost of one notebook is rupees 30.
41.Form the pair of linear equations in two variables from this situation by taking cost of one
book as Rs x and cost of one pen as y
a)3x + 2y =80 and 4x + 3y = 110 b) 2x + 3y =80 and 3x + 4y = 110 c) x + y = 80
and x + y = 110 d) 3x + 2y =110 and 4x + 3y = 80
42. which of the solution satisfied both the equation formed in (41)
a)x=10,y=20 b) x=20,y=10 c) x =15 , y = 15 d) None of these
43. find the cost of one pen?
a). Rs 20 b) Rs 10 c) Rs 5 d) Rs 15
44. find the total cost if they will purchase the same type of 15 notebooks and 12 pens
a) Rs 400 b) Rs 350 c) Rs 450 d) Rs 420
SOLUTION
COMPLETE QUESTION
Dipesh bought 3 notebooks and 2 pens for Rs. 80. His friend Ramesh said that price of each notebook could be Rs. 25. Then three notebooks would cost Rs.75, the two pens would cost Rs. 5 and each pen could be for Rs. 2.50. Another friend Amar felt that Rs. 2.50 for one pen was too little. It should be at least Rs. 16. Then the price of each Notebook would also be Rs.16. Lokesh also bought the same types of notebooks and pens as Dipesh.
He paid 110 for 4 notebooks and 3 pens
Let the cost of one notebook be x and that of pen be y .
(1) Which of the following set describe the given problem ?
(a) 2x + 3y = 80 and 3x + 4y = 110
(b) 3x + 2y = 80 and 4x + 3y = 110
(c) 2x + 3y = 80 and 4x + 3y = 110
(d) 3x + 2y = 80 and 3x + 4y = 110
( II ) Whether the estimation of Ramesh and Amar is applicable for Lokesh?
(a) Ramesh’s estimation is wrong but Amar’s estimation is correct.
(b) Ramesh’s estimation is correct but Amar’s estimation is wrong.
(c) Both estimation are correct.
(d) Ramesh’s estimation is wrong but Amar’s estimation is also wrong.
(III) What is the exact cost of the notebook?
(a) Rs 10
(b) Rs 20
(c) Rs 16
(d) Rs 24
( IV ) What is the exact cost of the pen?
(a) Rs 10
(b) Rs 20
(c) Rs 16
(d) Rs 24
(V) What is the total cost if they will purchase the same type of 15 notebooks and 12 pens.
(a) Rs 410
(b) Rs 200
(c) Rs 420
(d) Rs 240
EVALUATION
Here it is given that cost of one notebook be x and that of pen be y .
Then cost of 3 notebooks and 2 pens
= 3x + 2y
Again cost of 4 notebooks and 3 pens
= 4x + 3y
So by the given condition
3x + 2y = 80 - - - - - - - - - (1)
4x + 3y = 110 - - - - - - - - (2)
Which is set of equations to describe the given problem
Hence the set describe the given problem is
(b) 3x + 2y = 80 and 4x + 3y = 110
Now we solve from x and y
Multiplying Equation (1) by 3 and equation (2) by 2 we get
9x + 6y = 240
8x + 6y = 220
On substraction we get x = 20
From Equation (1) we get y = 10
Hence cost of one notebook is 20 and that of pen be 10
Ramesh said that price of each notebook could be Rs. 25
So Ramesh's estimation is wrong
Amar felt that Rs. 2.50 for one pen was too little. It should be at least Rs. 16
So Amar's estimation is wrong
(II) Whether the estimation of Ramesh and Amar is applicable for Lokesh
(d) Ramesh’s estimation is wrong but Amar’s estimation is also wrong.
Solving Equation (1) & Equation (2)
we get x = 20 & y = 10
(III) The exact cost of the notebook
(b) Rs 20
(IV) The exact cost of the pen
(a) Rs 10
The cost of 15 notebooks
= Rs ( 15 × 20 )
= Rs 300
The cost of 12 pens
= Rs ( 12 × 10 )
= Rs 120
Hence total cost
= Rs ( 300 + 120 )
= Rs 420
The total cost if they will purchase the same type of 15 notebooks and 12 pens.
(c) Rs 420
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