10, జులై 2014, గురువారం

Mallapragada's Mathematics (7th Standared-2)

                                                                           
                                                                                
1. A certain freezing process requires that room temperature be lowered from 500C at the rate of 50C every hour.  What will be the room temperature 10 hours after the process begins?



2. A merchant  on selling rice earns a profit of Rs. 20 per bag of fine  rice sold and loss Rs. 10 per bag of non-fine rice.



i) He sells 5000 bags of fine rice and 3000 bags of non – fine rice in a month.  What is his profit or loss in the month?

ii)What is the number of Fine rice bags he must sell to have neither profit nor loss, if the number of bags of non-fine rice sold is 6,400.



3. A cement company earns a profit of Rs. 10 per bag of white cement sold and a loss of Rs. 5 per bag of grey cement sold.



i)                  He company sells 8000 bags of white cement and 6000 bags of grey cement in a month.  What is its profit or loss?



ii)               What is the number of white cement bags it must sell to have neither profit nor loss, if the number of grey bags sold is 5,400



4. The temperature at 12 noon was 100 C  above zero.  If it decreases at the rate of 20 C per hour until mid-night at what time would the temperature be 60 C below zero. What would be the temperature at mid-night ?



5. In a class test (+3) marks are given for eery correct answer and (-2) marks are given for every incorrect answer and no marks for not attempting any question.

i) Radhika scored 20 marks.  If she has got 12 correct answers, how many questions has she attempted incorrectly?



ii) Mohini  scores (-5) marks in this test, though she has got 7 correct answers.  How many questions has she attempted incorrectly. 



6. An elevator descends into a mine shaft at the rate of 6 meters per minute. If  the  descent stars from 10m above the ground level.  How long will it take to reach – 350m



7. Krishna deposited Rs. 100 with her mother.  He withdraws Rs. 50 from her mother on the next now what is the money with his mother?



8. There is a class test for 25 marks.  Sheeta lost 10 marks and Gopi lost 8 marks.  What were marks at the test?



9. In a freezing process the temperature is to be lowered to    200 C. If the room temperature 300 C, how much it should be reduced?



10. Simplify  -1-2-3-……(-20)



11. Ram won 10 marbles in a game on a particular day.  He lost 3,5,6 and 8 on the following Find his net gain or loss.



12. A Fine of Rs. 5 is collected on every Rs. 100 to be deposited with post office. What was the fine a sum of Rs. 1200 ?



13. In a test of 15 Questions, every correct answer gets 5 marks and every wrong answers was get (-2) marks.  Rama answered all questions, out of which 8 are correct what is his total score?



14. In a quiz every right answer carries 10 marks and every wrong answer (2) marks.  It a total of 12 questions were asked of which 8 are correct, find the total score.



15. A fruit seller gains Rs. 200 on every dozen mangoes sold and loses Rs. 25 on every dozen apples sold.  If he sells 5 dozen mangoes and 10 dozen apples, what is his net gain or loss on the whole transactions?




































Om Sri Ram           Om Sri Ram           Om Sri Ram 
1. A certain freezing process requires that room temperature be lowered from 450C at the rate of 50C every hour.  What will be the room temperature 10 hours after the process begins?
Sol. The present  room temperature = 450
        Total decrease of temperature 10 houurs  = 10 x50 =500
         Temprature afer 10 years = 400 -450 = 50

2. A merchant  on selling rice earns a profit of Rs. 20 per bag of fine  rice sold and loss Rs. 10 per bag of non-fine rice.

i) He sells 5000 bags of fine rice and 3000 bags of non – fine rice in a month.  What is his profit or loss in the month?
Profit on 5000 bags of fine Rice = 5000 x 20 =1,00,000
Profit on 3000 bags on nonfine rice= 3000 x 10 = 30,000
Net profit = 100,000 -30,000= 70,000

ii)What is the number of Fine rice bags he must sell to have neither profit nor loss, if the number of bags of non-faine rice sold is 6,400.
Profit on fine rice = Loss on non-fine rice
But lloss on non fine rice = 6400 x 10 = 64000
No. of bags of fine rice sold = 64000/20 = 3,200

3. A cement company earns a profit of Rs. 10 per bag of white cement sold and a loss of Rs. 5 per bag of grey cement sold.

i)                  He company sells 8000 bags of white cement and 6000 bags of grey cement in a month.  What is its profit or loss?
Sol. Profit on 8000 white cement bags = 8000 x 10 = 80,000
        Loss on 6000 grey cement bags = 6000 x 5 = 30,000
        Net profit       = 80,000 =- 30,000 = 50,000 Profit.

ii)               What is the number of white cement bags it must sell to have neither profit nor loss, if the number of grey bags sold is 5,400
Profit on white cement bags = loss on grey cement bags.
Loss on grey cement bags   = 5 x 5400 = 27,000
Number of white cement bags : 27,000/10 = 2700

4. The temperature at 12 noon was 100 C  above zero.  If it decreases at the rate of 20 C per hour until mid-night at what time would the temperature be 60 C below zero. What would be the temperature at mid-night ?
Sol. The temperature at 12 noon = 100
            Given temperature = -60 C
        Diff. between the temperature =  100 – (-60) = 160
        Time lasted = 16 /2 =80

5. In a class test (+3) marks are given for every correct answer and (-2) marks are given for every incorrect answer and no marks for not attempting any question.
i) Radhika scored 20 marks.  If she has got 12 correct answers, how many questions has she attempted incorrectly?
Sol. Radhika’s score    = 20
        No. of correct answers     = 12
        And marks for correct answers = 12 x 3 =36
        Marks for incorrect answers = 36-20 = 18
        Number of incorrect answers = 18/2 =9

ii) Mohini  scores (-5) marks in this test, though she has got 7 correct answers.  How many questions has she attempted incorrectly. 
Mohini’s score           = -5
Marks for correct answers = 7 x 3 = 21
Marks for incorrect answers = -5 -21 = -26
Number of incorrect answers = -26/2 = -13

6. An elevator descends into a mine shaft at the rate of 6 meters per minute.  If  the  descent stars from 10m above the ground level.  How long will it take to reach – 350m
Sol. Total length to be descend = -350 -10 = -360m
        Rate of the speed of the elevator = 6m per minute
        Total time to descend = 360/6 = 60 minuts = 1 hour

7. Krishna deposited Rs. 100 with her mother.  He withdraws Rs. 50 from her mother on the next now what is the money with his mother?
Sol. Money deposited  = Rs. 100
        Money With drawn = Rs 50
        Money withmother  = Rs. 100 - 50 =Rs. 50

8. There is a class test for 25 marks.  Sheeta lost 10 marks and Gopi lost 8 marks.  What were marks at the test?
Sol. Total marks for the test = 25
        Marks lost by sheetal = 10
        Sheetal’s marks = 25-10 = 15
       Marks lost by Gopi  = 8
      Gopi marks   = 25 -8 = 17

9. In a freezing process the temperature is to be lowered to    200 C. If the room temperature 300 C, how much it should be reduced?
sol. Required temperature = -200
       Room Temparature = 300
       The temperature to be reduced by = 30 –(-20)= 500C

10. Simplify  -1-2-3-……(-20)
      (-1-20)+(-2-19)+(-3-18)+(-4-17)+(-5-16)+(-6-15)+(-7-14)+         
      (-8-13)+ (-9-12) +(-10-11) = 10 x (-21) =-210

11. Ram won 10 marbles in a game on a particular day.  He lost 3,5,6 and 8 on the following Find his net gain or loss.
Numbers of marbles won by ram =10
Number of marbles lost by Ram = 3+5+6+8 =22
Net loss = 10 -22 =-12
12. A Fine of Rs. 5 is collected on every Rs. 100 to be deposited with post office. What was the fine a sum of Rs. 1200 ?
For every hundred thefine is Rs. 5
For Rs. 1200 the fine = 5 x 12 = Rs. 60

13. In a test of 15 Questions, every correct answer gets 5 marks and every wrong answers was get (-2) marks.  Rama answered all questions, out of which 8 are correct what is his total score?
Number of correct answers = 8
Marks for 8 correct answers = 8 x 5 = 40
Number of wrong answers = 15-8= 7
Marks for wrong answers = 7 x (-2) = -14
Total Marks = 40 + (-14) = 26

14. In a quiz every right answer carries 10 marks and every wrong answer (-2) marks.  It a total of 12 questions were asked of which 8 are correct, find the total score.
Sol. Right answers = 8
Marks for right answers = 8 x 10 = 80
Wrong answers = 4
Marks for wrong answers = 4 x (-2) = -8
Total marks = 80 – 8= 72

15. A fruit seller gains Rs. 200 on every dozen mangoes sold and loses Rs. 25 on every dozen apples sold.  If he sells 5 dozen mangoes and 10 dozen apples, what is his net gain or loss on the whole transactions?
Gain 5 dozen mangos = 5 x 200 = 1000
Loss on 10 dozen apples    = 10 x 25 =250
Net gain     = Rs. 1000 – 250 = Rs. 750