which of the following is the best integer approximation of sqr(2)+sqr(5)+sqr(7)??
A) 6
B) 7
C) 8
D) 9
E) 10
Some trick to calculate sqr?
A) 6
B) 7
C) 8
D) 9
E) 10
Some trick to calculate sqr?
Sqr(2) will be btwn 1 and 2
Sqr(5) will be btwn 2 and 3
Sqr(7) will be btwn 2 and 3
so min would be 5 and maximum would be 8. So our answer lies btwn 5 and 8.
Now out of the given ans choice it woould be 6,7,8
Now intelligent guessing needs to be done
Sqr(2) <1.5 as btwn 1 and 4 which are square numbers lies 2 and 3 and sqr (3) >1.5
and approximating more as there are 2 nos btwn 1and 4
take sqr(2) ~1.33
similarly
Sqr(5) <<2.5 and sqr (7) >2.5 as there are 4 nos 5,6,7,8 btwn 4 and 9 the two square nos.
and approximating more as there are 4 nos btwn 9and 4
take sqr(5) ~ 2.2
sqr(7) ~ 2. 6
Total = 1.33 + 2.2 + 2.6 = 6.13
Approximating take it as 6
