CAT 2021 Quantitative Aptitude (QA) Master Hub

The strength of an indigo solution in percentage is equal to the amount of indigo in grams per $100 \mathrm{cc}$ of water. Two $800 \mathrm{cc}$ bottles are filled with indigo solutions of strengths $33 \%$ and $17 \%$, respectively. A part of the solution from the first bottle is thrown away and replaced by an equal volume of the solution from the second bottle. If the strength of the indigo solution in the first bottle has now changed to $21 \%$ then the volume, in cc, of the solution left in the second bottle is

How many three-digit numbers are greater than $100$ and increase by $198$ when the three digits are arranged in the reverse order?

The amount Neeta and Geeta together earn in a day equals what Sita alone earns in 6 days. The amount Sita and Neeta together earn in a day equals what Geeta alone earns in 2 days. The ratio of the daily earnings of the one who earns the most to that of the one who earns the least is

Anu, Vinu and Manu can complete a work alone in 15 days, 12 days and 20 days, respectively. Vinu works everyday. Anu works only on alternate days starting from the first day while Manu works only on alternate days starting from the second day. Then, the number of days needed to complete the work is

If $\mathrm{x}_{0}=1, \mathrm{x}_{1}=2$, and $\mathrm{x}_{\mathrm{n}+2}=\frac{1+x_{n+1}}{x_{n}}, n=0,1,2,3 \ldots \ldots$., then $x_{2021}$ is

If $5-\log _{10} \sqrt{1+x}+4 \log _{10} \sqrt{1-x}=\log _{10} \frac{1}{\sqrt{1-x^{2}}}$,then $100 \mathrm{x}$ equals

Suppose hospital $A$ admitted $21$ less Covid infected patients than hospital $B$, and all eventually recovered. The sum of recovery days for patients in hospitals $A$ and $B$ were $200$ and $152$, respectively. If the average recovery days for patients admitted in hospital $A$ was $3$ more than the average in hospital $B$ then the number admitted in hospital $A$ was

If r a constant such that $|x^2 - 4x - 13| = r$ has exactly three distinct real roots, then the value of r is

Anil invests some money at a fixed rate of interest, compounded annually. If the interests accrued during the second and third year are $₹ 806.25$ and $₹ 866.72,$ respectively, the interest accrued, in INR, during the fourth year is nearest to

A circle of diameter $8$ inches is inscribed in a triangle ABC where $\angle A B C=90^{\circ}$. If $B C=10$ inches then the area of the triangle in square inches is

Two trains cross each other in $14$ seconds when running in opposite directions along parallel tracks. The faster train is $160$ m long and crosses a lamp post in $12$ seconds. If the speed of the other train is $6$ km/hr less than the faster one, its length, in m, is

A basket of $2$ apples, $4$ oranges and $6$ mangoes costs the same as a basket of $1$ apple, $4$ oranges and $8$ mangoes, or a basket of $8$ oranges and $7$ mangoes. Then the number of mangoes in a basket of mangoes that has the same cost as the other baskets is

Amar, Akbar and Anthony are working on a project. Working together Amar and Akbar can complete the project in $1$ year, Akbar and Anthony can complete in $16$ months, Anthony and Amar can complete in $2$ years. If the person who is neither the fastest nor the slowest works alone, the time in months he will take to complete the project is

If the area of a regular hexagon is equal to the area of an equilateral triangle of side $12$ cm , then the length, in cm , of each side of the hexagon is

Amal purchases some pens at ₹ $8$ each. To sell these, he hires an employee at a fixed wage. He sells $100$ of these pens at $₹ 12$ each. If the remaining pens are sold at $₹ 11$ each, then he makes a net profit of ₹ $300$, while he makes a net loss of ₹ $300$ if the remaining pens are sold at ₹ $9$ each. The wage of the employee, in INR, is

The number of integers n that satisfy the inequalities $|n -60| < |n-100| <| n-20|$ is

Identical chocolate pieces are sold in boxes of two sizes, small and large. The large box is sold for twice the price of the small box. If the selling price per gram of chocolate in the large box is $12 \%$ less than that in the small box, then the percentage by which the weight of chocolate in the large box exceeds that in the small box is nearest to

The natural numbers are divided into groups as (1), $(2,3,4),(5,6,7,8,9), \ldots .$. and so on. Then, the sum of the numbers in the 15th group is equal to

Onion is sold for $5$ consecutive months at the rate of Rs $10,20,25,25$, and $50$ per kg, respectively. A family spends a fixed amount of money on onion for each of the first three months, and then spends half that amount on onion for each of the next two months. The average expense for onion, in rupees per kg, for the family over these $5$ months is closest to

Suppose the length of each side of a regular hexagon $ABCDEF$ is $2$ cm. It $T$ is the mod point of $CD$, then the length of $AT$, in cm, is

$$f(x) = \frac{x^2+2x-15}{x^2-7x-18}$ is negative if and only if

The number of groups of three or more distinct numbers that can be chosen from 1,2, $3,4,5,6,7$ and $8$ so that the groups always include $3$ and $5$, while $7$ and $8$ are never included together is

Let $D$ and $E$ be points on sides $A B$ and $A C$, respectively, of a triangle $A B C$, such that $A D: B D=2: 1$ and $A E: C E=2: 3$. If the area of the triangle $A D E$ is $8 \mathrm{ sq } \mathrm{cm}$, then the area of the triangle $ABC$ , in sq cm , is

Two trains $A$ and $B$ were moving in opposite directions, their speeds being in the ratio $5: 3$. The front end of $A$ crossed the rear end of $B$ $46$ seconds after the front ends of the trains had crossed each other. It took another $69$ seconds for the rear ends of the trains to cross each other. The ratio of length of train $A$ to that of train $B$ is

Anil, Bobby and Chintu jointly invest in a business and agree to share the overall profit in proportion to their investments. Anil's share of investment is $70\%$. His share of profit decreases by Rs. $420$ if the overall profit goes down from $18\%$ to $15\%$. Chintu's share of profit increases by Rs. $80$ if the overall profit goes up from $15\%$ to $17\%$. The amount, in INR, invested by Bobby is