fiza gupta wrote:How many integers between 324,700 and 458,600 have a 2 in the tens digit and 1 in the units digit?
(A) 1,339
(B) 1.352
(C) 1,353
(D) 10,030
(E) 10,300
A nice rule says:
the number of integers from x to y inclusive equals y - x + 1
So, the number of integers from 324,700 to 458,600 = 458,600 - 324,700 + 1 =
133901
ASIDE: We can safely round this number
133900 (you'll see why shortly)
Now let's look at how frequently we have a
2 in the tens digit and
1 in the units digit.
Integers from 1 to 100:
21 - 1 integer
Integers from 101 to 200: 1
21 - 1 integer
Integers from 201 to 300: 2
21 - 1 integer
Integers from 301 to 400: 3
21 - 1 integer
.
.
.
As we can see, for every 100 integers, there's 1 integer with a
2 in the tens digit and
1 in the units digit.
In other words, 1/100 of all integers have a
2 in the tens digit and
1 in the units digit.
So, among the
133900 integers in question 1/100 of them meet the given condition.
(1/100)(
133900) = 1339
Answer:
A
Cheers,
Brent $$$$
