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NTA JEE Main 9th April 2019 Shift 2 - Mathematics

For the following questions answer them individually

Some identical balls are arranged in rows to form an equilateral triangle. The first row consists of one ball, the second row consists of two balls and so on. If 99 more identical balls are added to the total number of balls used in forming the equilateral triangle, then all these balls can be arranged in a square, whose each side contains exactly 2 balls less than the number of balls each side of the triangle contains. Then the number of balls used to form the equilateral triangle is:

If the tangent to the parabola $$y^2 = x$$ at a point $$(\alpha, \beta)$$, $$(\beta > 0)$$ is also a tangent to the ellipse, $$x^2 + 2y^2 = 1$$, then $$\alpha$$ is equal to:

If $$f(x) = [x] - \left[\frac{x}{4}\right]$$, $$x \in R$$, where $$[x]$$ denotes the greatest integer function, then:

A water tank has the shape of an inverted right circular cone, whose semi-vertical angle is $$\tan^{-1}\left(\frac{1}{2}\right)$$. Water is poured into it at a constant rate of 5 cubic m/min. Then the rate (in m/min), at which the level of water is rising at the instant when the depth of water in the tank is 10 m; is:

Let P be the plane, which contains the line of intersection of the planes, $$x + y + z - 6 = 0$$ and $$2x + 3y + z + 5 = 0$$ and it is perpendicular to the xy-plane. Then the distance of the point (0, 0, 256) from P is equal to:

Two newspapers A and B are published in a city. It is known that 25% of the city population reads A and 20% reads B while 8% reads both A and B. Further, 30% of those who read A but not B look into advertisements and 40% of those who read B but not A look into advertisements, while 50% of those who read both A and B look into advertisements. Then the percentage of the population who look into advertisements is: