SSC CGL 202011)The average of five consecutive odd numbers is m. If the next three odd numbers are also included, then what is the increase in the average ?
3
Let five odd numbers be (x - 4), (x - 2), x, (x + 2), (x + 4) ; Average = \((x - 4)+ (x - 2)+ x+ (x + 2)+ (x + 4)\over5\) = m; x = m; Therefore, Sum of 5 number = 5m; New average = (Sum of 5 number + Sum of 3 number) / 8; ⇒ \({5m+m+6+m+8+m+10\over8} ={8m+24\over8}=m+3\);
SSC CGL 202012)The average of 60 student’s results is 38. If the average of the first 22 students is 36, and that of the last 32 students is 32, then the average result of the remaining students is:
77.33
Average of results of 60 students = 38; Total of results of 60 students = 60 x 38 = 2280; Average of results of 22 students = 36; Total of results of 22 students = 36 x 22 = 792; Average of results of 32 students = 32; Total of results of 32 students = 32 x 32 = 1024; Sum of results of the remaining 6 students = 2280 - 792 - 1024 = 464; Required average = \({464\over6} = 77.33\)
SSC CGL 202013)24 students collected money for donation. The average contribution was Rs. 50. Later on, their teacher also contributed some money. Now the average contribution is Rs. 56. The teacher’s contribution is:
Rs. 200
Total money contribution by 24 students = Average x No. of students = 50 x 24 = 1200; Total money contribution by 24 students and their teacher = 56 x 25 = 1400 ; Teacher’s contribution = 1400 - 1200 = Rs.200
SSC CGL 202014)The average of the marks of 30 boys is 88, and when the top two scores were excluded, the average marks reduced to 87.5. If the top two scores differ by 2, then the highest mark is:
96
Average marks of 30 students = 88; Let top two marks be x and x + 2. According to the question, \(30\times88-x-(x+2)=28\times87.5\); x= 94; So highest marks = x + 2 = 94 + 2 = 96
SSC CGL 202015)The average height of 5 boys is 175 cm. A sixth boy joined the group and the average height of all the boys in the group now increased by 1 cm. The height of the sixth boy is:
181 cm
Height of sixth boy = 175 cm + total increase = (175 + 1 x 6) = 181 cm
SSC CGL 201616)The average of marks of 17 students in an examination was calculated as 71. But it was later found that the mark of one student had been wrongly entered as 65 instead of 56 and another as 24 instead of 50. The correct average is
72
SSC CGL 202017)The average of some numbers is 54.6. If 75% of the numbers are increased by 5.6 each, and the rest are decreased by 8.4 each, then what is the average of the numbers so obtained?
56.7
New average of the numbers = (average + increment/decrements);
The average of some numbers = 54.6;
75% of the numbers are increased by 5.6 each, and the rest are decreased by 8.4 each so,
New average of the numbers = \(54.6 +\) \((5.6 \times 75/100 - 8.4 \times 25/100)\) = 54.6 + 4.2 - 2.1 = 56.7
SSC CGL 202018)The average of 24 numbers is 56. The average of the first 10 numbers is 71.7 and that of the next 11 numbers is 42. The next three numbers i.e. 22nd, 23rd and 24th are in the ratio, \({1\over2}:{1\over3}:{5\over12}\) . What is the average of the 22nd and 24th numbers?
60.5
22nd number : 23rd number : 24th number = \({1\over2}:{1\over3}:{5\over12}\) = 6 : 4 : 5
According to the question, \(10\times 71.7+11\times 42+6k+4k+5k= 24\times 56\) ; ⇒ k = 11 ;
Required average = \({6k+5k\over2}= {11\times11\over2}= 60.5\)
SSC CHSL 202119)The average weight of 30 persons of group A is 3 kg more than the average weight of 25 persons of group B. The average weight of 25 persons of group B is 2.5 kg more than the average weight of 20 persons of group C. If the total weight of 30 persons of group A is 1725 kg, then what will be the average weight of the persons of group A and group C taken together (in kg)?
55.3
SSC CHSL 202120)30 people went to a restaurant for a dinner party, 20 of them paid Rs.880 each and each of the rest of them paid Rs.110 more than the average of the total expenses. What was the total expense (in Rs.) for the dinner?
28,050