IPMAT (I) 2021 QASA
The number of positive integers that divide (1890) × (130) × (170) and are not divisible by 45 is:
Answer: 320
Explanation :
We first need to find all factors of (1890) × (130) × (170) and then remove those factors which are divisible by 45.
(1890) × (130) × (170) = (2 × 33 × 5 × 7) × (13 × 2 × 5) × (17 × 2 × 5)
⇒ 1890 × 130 × 170 = 23 × 33 × 53 × 7 × 13 × 17
∴ Total factors = (3 + 1)(3 + 1)(3 + 1)(1 + 1)(1 + 1)(1 + 1) = 512
Now for factors that are divisible by 45, least power of 3 should be 2 and that of 5 should be 1. Powers of 2, 7, 13 and 17 can be anything.
∴ Total factors which are divisible by 45 = 4 × 2 × 3 × 2 × 2 × 2 = 192
⇒ Number of factors which are not divisible by 45 = 512 - 192 = 320.
Hence, 320.
Workspace:
The sum up to 10 terms of the series 1 × 3 + 5 × 7 + 9 × 11 + . . is
Answer: 5310
Explanation :
Workspace:
It is given that the sequence {xn} satisfies x1 = 0, xn+1 = xn + 1 + for n = 1,2, . . . . . Then x31 is
Answer: 960
Explanation :
Workspace:
There are 5 parallel lines on the plane. On the same plane, there are ‘n’ other lines that are perpendicular to the 5 parallel lines. If the number of distinct rectangles formed by these lines is 360, what is the value of n?
Answer: 9
Explanation :
Workspace:
There are two taps, T1 and T2, at the bottom of a water tank, either or both of which may be opened to empty the water tank, each at a constant rate. If T1 is opened keeping T1 closed, the water tank (initially full) becomes empty in half an hour. If both T1 and T2 are kept open, the water tank (initially full) becomes empty in 20 minutes. Then, the time (in minutes) it takes for the water tank (initially full) to become empty if T2 is opened while T1 is closed is
Answer: 60
Explanation :
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A class consists of 30 students. Each of them has registered for 5 courses. Each course instructor conducts an exam out of 200 marks. The average percentage marks of all 30 students across all courses they have registered for, is 80%. Two of them apply for revaluation in a course. If none of their marks reduce, and the average of all 30 students across all courses becomes 80.02%, the maximum possible increase in marks for either of the 2 students is
Answer: 6
Explanation :
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What is the minimum number of weights which enable us to weigh any integer number of grams of gold from 1 to 100 on a standard balance with two pans? (Weights can be placed only on the left pan)
Answer: 7
Explanation :
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If one of the lines given by the equation 2𝑥2 + axy + 3y2 = 0 coincides with one of those given by 2x2+ b𝑥𝑦 - 3𝑦2 = 0 and the other lines represented by them are perpendicular then 𝑎2 + 𝑏2 =
Answer: 26
Explanation :
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If a function f(a) = max (a, 0) then the smallest integer value of ‘x’ for which the equation f(x - 3) + 2f(x + 1) = 8 holds true is:
Answer: 3
Explanation :
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In a class, 60% and 68% of students passed their Physics and Mathematics examinations respectively. Then atleast ________ percentage of students passed both their Physics and Mathematics examinations.
Answer: 28
Explanation :
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