1. In a class there are 60 students out of whom 15 per cent are girls. Each girl’s monthly fee is Rs 250 and each boy’s monthly fee is 34 percent more than a girl. What is the total monthly fee of girls and boys together?
Ans:1 No. of girls = 60×15/100 = 9 Each boy’s fee = 250 x 1.34 = 335 Total fee = 9×250 + 51×335 = 2250+17085 = 19335
2. The ratio of the present ages of Anubha and her mother is 1:2. The ratio of their ages 6 years hence would be 11:20. What was the ratio of their ages 9 years ago?
Ans:4 Let their present ages be a and 2a. According to the question, (a+6):(2a+6) = 11:20 => 20a+120 = 22a+66 => a = 27 Required ratio = 27-9 : 54-9 = 18:45 = 2:5
3. The breadth of a hall is 3/4th times its length. If the area of the hall be 192 square metres, then what is the perimeter of the hall?
Ans:4 Let Length = lBreadth = 3l/4
Given area = 3l2/4 = 192
So, l2 = 192 x 4/3 = 256
or l = 16m
So, Breadth = 3l/4 = 12m
Perimeter = 2 (l+b) = 56
4. The salary of P is first decreased by 25% and then increased by 20%. Similarly, the salary of Q is first increased by 30% and then reduced by 20%. Then, find the ratio of salary of P and Q finally, if initially the salary of P and Q were equal?
Ans:2 Let the salary of P initially be Rs 100. After 25% decrease, salary of P becomes Rs 75. Now, the salary is increased by 20%. So, the final salary of P = 75 * 1.2 = Rs 90 Let the salary of Q initially be Rs 100. After 30% increase, salary of Q becomes Rs 130. Now, the salary is decreased by 20%. So, the final salary of Q = 130 * 0.8 = Rs 104. Therefore, the ratio of salary of P and Q finally = 90: 104 = 45:52.
5. Gaurav spent rs 38,460 on the renovation of his home, rs 24,468 on buying home theatre and the remaining 28% of the total amount he had as cash with him. What was the total amount?
Ans:3 Let the total amount be ‘a’ 72% of the total amount he spent on renovation and buying home theatre 72/100 x a = ( 24,468 + 38,460) 72/100 x a = 62,928 A = rs 87400
6. Two persons are walking in the same direction at rates 3 kmph and 6 kmph. A train comes running from behind and passes them in 9 and 10 seconds. The length of the train is?
Ans:2 Let the speed of the train be x kmph and its length be y metres Then, y = (x – 3) X 5/18 X 9——— (1) y = (x – 6) X 5/18 X 10———– (2) Solving (1) & (2) Speed of the train = 33 kmph Therefore length = 75 metres
7. Chinnappa could row 3/2 km upstream in 45/4 minutes and return in 15/2 minutes. What is the speed of the stream?
Ans:1 Given, Chinnappa could row 3/2 km upstream in 45/4 minutes. In hours = (45/4)/60 = 3/16 hour. => His speed upstream = (3/2)/(3/16) = 8 km/h Also given, he could row 3/2 km downstream in 15/2 minutes. In hours = (15/2)/60 = 1/8 hour. => His speed downstream = (3/2)/(1/8) = 12 km/h ∴ Speed of the stream = (12 – 8)/2 = 2 km/h
8. 10 men and 15 women can finish a work in 6 days. One man alone finished that work in 100 days. In how many days a woman alone can finish the work?
Ans:2 Let the total work be 1 unit.One man can finish this 1 unit work in 100 days means in one day 1 man can do 1/100 unit of work.
So 10 men can do = 10 X 1/100 = 1/10 unit of work.
According to the question 10 men and 15 women finish a work in 6 days means in 1 day they can finish 1/6th unit of work.
Hence, 15 woman’s work of a day = 1/6-1/10=1/15 unit
∴ a woman alone will take
= 15 X 15 = 225 days
9. The average of the ages of Sunanda, Amrita and Manya is 43 and the average of the ages of Sunanda, Manya and Kapil is 49. If Kapil is 54 years old, what is Amrita’s age?
Ans:5 Sum of the ages of Sunanda, Amrita and Manya = 43 X 3 = 129 Sum of the ages of Sunanda , Kapil and Manya = 49 X 3= 147 Given that, the age of Kapil = 54 years Therefore, Sum of the ages of Sunanda and Manya = 147 – 54 =93 Then, Amrita’s age = 129 – 93 = 36 years. Hence, option 5.
10. A class of 18 students scored 29 marks on an average out of 50 in English. If 2 students who scored 41 and 47 are replaced by 2 new students who scored 33 and 37 marks, then will be the new average of the class?
Ans:2 Previous total score of class in English = Average score X strength of the class = 29 X 18 = 522 Now two students who scored 41 and 47 marks in English are replaced by 2 new students who scored 33 and 37 marks in the same subject. Therefore new total score = 522 – (41 + 47) + (33 + 37) = 504 So, the new average of the class = 504/18 = 28
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