11) In seven given numbers, the average of first four numbers is 4 and that of last four numbers is also 4. If the average of these seven numbers is 3, the fourth number is
a) 3
b) 4
c) 7
d) 11
12) The average of 100 observations was calculated as 40. It was found later on that one of the observations was misread as 83 instead of 53. The correct average is
a) 39
b) 39.7
c) 40.3
d) 42.7
13) A man spends Rs 1800 monthly on an average for the first four months and Rs 2000 monthly for the next eight months and saves Rs 5600 a year. His average monthly income is
a) Rs 2000
b) Rs 2200
c) Rs 2400
d) Rs 2600
14) Three years ago, the average age of a family of 5 members was 17 yr. A baby having been born, the average age of the family is the same today. The present age of the baby is
a) 2 yr
b) 2.4 yr
c) 3 yr
d) 1.5 yr
15) The average of marks of a student in 7 subjects is 75. His average in 6 subjects excluding science is 72. How many marks did he get in science ?
a) 72
b) 90
c) 93
d) None of these
16) The average weight of 29 students is 28 kg. by the admission of a new student, the average weight is reduced to 27.8 kg. The weight of the new student is
a) 22 kg
b) 21.6 kg
c) 22.4 kg
d) 21 kg
17) The average age of 30 students of a class is 12 yr. The average age of a group of 5 of the students is 10 yr and that of another group of 5 of them is 14 yr. what is the average age of the remaining students ?
a)8 yr
b) 10 yr
c) 12 yr
d) 14 yr
18) The age of Shaurya and Kauravki is in the ratio 2 : 6. After 5 years, the ratio of their ages will become 6 : 8. Find the average of their ages after 10 years.
(a) 12
(b) 13
(c) 17
(d) 24
19) The average of ten numbers is 7. If each number is multiplied by 12, then the average of the new set of numbers is
(a) 7
(b) 19
(c) 82
(d) 84
20) 30 oranges and 75 apples were purchased for Rs 510. If the price per apple was Rs 2, then the average price of oranges was
(a) 12
(b) 14
(c) 10
(d) 15