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H Harsh Kankaria

7. An elevator descends into a mine shaft at the rate of 6 m/min. If the descent starts from 10 m above the ground level, how long will it take to reach – 350 m.

H Harsh Kankaria
Given, Marks for every correct answer = Marks for every wrong answer = (i) According to question, Marks obtained by Radhika = Number of correct answers =  Marks obtained for correct answers =  Marks obtained for incorrect answers = Total marks – Marks obtained for correct answers  Number of incorrect answers =  Therefore, Radhika attempted 8 questions incorrectly. (ii)  According to...

H Harsh Kankaria
Given, Temperature at 12 noon =  Final temperature =   Decrease in temperature =  Time taken for the temperature  to decrease by =   Time taken for the temperature  to decrease by =  Now, Time until mignight =   Decrease in temperature in  =  Therefore, temparature at midnight =  Therefore, temperature at mid-night will be  below zero.

H Harsh Kankaria
Five pairs of integers such that  are:

H Harsh Kankaria
(a) Given,  A number divided by 1 gives the number itself.              (b) The product is negative, therefore there must be odd number of negative integers.                   (c) A number divided by itself gives 1               (d) The product is positive, therefore there must be even number of negative integers.                   (e) A number divided by 1 gives the number itself.     ...

H Harsh Kankaria
(a) a = 12, b = – 4, c = 2    L.H.S =  R.H.S =  Therefore. Hence verified.   (b) a = (–10), b = 1, c = 1 L.H.S =  R.H.S =  Therefore. Hence verified.

H Harsh Kankaria
Points to keep in mind:  When we divide a negative integer by a positive integer, we first divide them as whole numbers and then put a minus sign (–) before the quotient. When we divide a positive integer by a negative integer, we first divide them as whole numbers and then put a minus sign (–) before the quotient. When we divide a negative integer by a negative integer, we first divide them as...

H Harsh Kankaria
(i) is true only for . (ii) Taking,  Hence, this is true for every integer .

H Harsh Kankaria
When we divide a negative integer by a negative integer, we first divide them as whole numbers and then put a positive sign (+). (a)           (b)          (c)

H Harsh Kankaria
When we divide a positive integer by a negative integer, we first divide them as whole numbers and then put a minus sign (–) before the quotient. (a)         (b)          (c)

H Harsh Kankaria
When we divide a negative integer by a positive integer, we first divide them as whole numbers and then put a minus sign (–) before the quotient (a)             (b)               (c)              (d)

H Harsh Kankaria
(a)Given,   The product is positive, therefore there should be even number of negative integers.              (b) Given, The product is negative, therefore there should be odd number of negative integers. (c)          The product is negative, therefore there should be odd number of negative integers. (d) The product is positive, therefore there should be even number of negative integers.

H Harsh Kankaria
Given, Profit earned by selling 1 bag of white cement =  Loss on 1 bag of grey cement =  Loss on 6400 bags of grey cement =  To be neither in profit nor loss, the profit from white cement must be  Number of white cement bags to be sold =  Therefore the company has to sell 4000 white cement bags.

H Harsh Kankaria
Given, Profit earned by selling 1 bag of white cement =  Profit earned by selling 3000 bags of white cement=  Loss on 1 bag of grey cement = Loss of 5000 bags of grey cement =  Total earnings =  This means that the company incurred a loss of

H Harsh Kankaria
Given, Total questions =  Marks for correct answer =  Marks for incorrect answers =  Marks for unattempted question =  According to question, Heena gets two correct and five incorrect answers. Therefore, number of unattempted questions =  Total marks =  Therefore, Heena scored 0 marks.

H Harsh Kankaria
Given, Total questions =  Marks for correct answer =  Marks for incorrect answers =  Marks for unattempted question =  According to question, Reshma gets five correct answers and five incorrect answers Total marks =  Therefore, Reshma scored 15 marks.