A man walks up a mountain at the rate of 2 km an hour and down by a way 6 km longer at the rate of 7/2 km an hour. He is out eight hours altogether. How far has he walked?
OPtion
1) 43 km
2) 38 km
3) 32 km
4) 29 km
5) 26 km
6) 22 km
7) 20 km
8) 19 km
9) 17 km
10) None of these
Solution
Let the way up be x km
Time taken to climb up = x/2 hours.
The way down = (x+6)km
Time taken to climb down =(x+6)/(7/2)= 2(x+6)/7
Therefore the total time of the journey = (x/2)+{2(x+6)/7}=8
solve x = 8
Total distance = x+x+6 = 22km.
option 6
Let there are n children, then each child will have n-1 gifts.
Total number of gift=total number of children*number of gifts per child
n(n-1)=132
solve
n can not be -ve
n=12
(1) No. of words having all letters different = 6*5*4*3 = 360
(2) No. of words having any one letter repeated
=(2*1)*(5*4*3*2*1/3*2*1*2*1)*(4*3*2*1/2*1) = 240
(3) No. of words having two letter repeated = (1)*(4*3*2*1/2*1*2*1) = 6
Total words = 360+240+6 = 606
ans 606
option 5
A teacher on attempting to arrange the students for mass drill in the form of a solid square found that 24 students were left over. When he increased the size of the square by one student he found that he was short of 25 students. Find the number of students.
Let the number of students in one side = x
Total number of students = x^2+24 (because 24 students were left)
When size of the square in increased by 1
then total number of students = (x+1)^2 - 25 (25 students were short)
Now the number of students in same,
x^2 + 24 = (x+1)^2 - 25
solve
x = 24
Total number of students = 24^2 + 24 = 600
option 6
A person borrows Rs.4500 and promises to pay back (without any interest) in 30 installment, each of value Rs.10 more than the last (preceding one). Find the last installment.
Let a be the first installment
Successive installment are
a, a+10, a+20
here d=10, n=number of installment =30
Solve by using A.P. Series
S=n/2(2a+(n-1)d)=4500
solve
first intallment 5, last intallment 295
option 6