Question

.Marks obtained by Radhika in quarterly and half yearly exams of mathematics are 60 re 60 and 70 respectively.
Based on the above information, answer the following questions.
(i) Minimum marks, she should get in the annual exam to have an average of atleast 70 marks is
(a)80 (b) 85 (c) 75 (d) 90
(ii) Maximum marks, she should get in the annual exam. To have an average of atmost 75 marks is
(a)85 (b) 90 (c) 95 (d) 80
(iii) Range of marks in annual exam., so that the average mark is atleast 60 and atmost 70 is
(a) [60,70] (b) [50,80] (c) [50,70] (d) [60,80]
( iv) If she scored atleast 20 and atmost and atmost 80 marks in annual exam., then the range of average marks is
(a) [50,70] (b) [60,70] (c) [50,60] (d) [50,80]

Answer 1

Answer:

please recheck the question

Step-by-step explanation:

some spelling mistakes are 5hrer

Answer 2

The correct answers are (i) (a)$80$, (ii)(c)$95$. (iii)(b)$[50,80]$, (iv)(a)$[50,70]$.

Step-by-step explanation:

Marks obtained by Radhika in quarterly exam$=60$

in half-yearly exam$=70$

(i) average mark atleast$=70$

so minimum mark$=$total mark-sum of half-yearly and quarterly mark

                               =$(70*3)-$$(60+70)$

                               $=210-130=80$

(ii) average marks atmost$=75$

so maximum mark$=$total mark-sum of half-yearly and quarterly mark

                              $=(75*3)-(60+70)$

                              $=225-130=95$

(iii) the average mark is atleast$=60$ and atmost$=70$

so minimum mark$=$total mark-sum of half-yearly and quarterly mark

                             =$(60*3)-$$(60+70)$

                             $=180-130=50$

maximum mark=total mark-sum of half-yearly and quarterly mark

                        $=(70*3)-(60+70)$

                        $=210-130=80$

so the range of mars in the annual exam$=[50,80]$

(iv)she scored atleast$=20$ and atmost$=80$ in the annual exam

so total mark minimum$=60+70+20=150$

total mark maximum$=60+70+80=210$

so average mark minimum$=150/3=50$

average mark maximum$=210/3=70$

so range of average marks$=[50,70]$