CAT / #Quantitative Ability

October 28, 2017 @ 11:42 AM

Quantitative Ability - Chain Rule

Important Formulas:

1. Direct Proportion:

Two quantities are said to be directly proportional, if on the increase (or decrease) of the one, the other increases (or decreases) to the same extent.

E.g. Cost is directly proportional to the number of articles. (More Articles, More Cost)

2Indirect Proportion:

Two quantities are said to be indirectly proportional if on the increase of the one, the on other decreases to the same extent and vice-versa.

E.g. The time taken by car is covering a certain distance is inversely proportional to the speed of the car. (More speed, Less is the time to cover a distance.)

Note: In solving problems by chain rule, we compare every item with the term to be found out:

Solved Illustrations:

Question 1)

If the cost of X meters of wire is d rupees, then what is the cost of y meters of wire at the same rate?

A) Rs. xy/d

B) Rs. yd/x

C) Rs. (yd)

D) Rs. (xd)

Answer: option B


Cost of x metres = Rs. d.

Cost of 1 metre = Rs. d/x

Cost of Y metres = Rs. (d/x * x.y) = rs. yd/x

Question 2)

39 persons can repair a road in 12 days, working 5 hours a day. In how many days will 30 persons, working 6 hours a day, complete the work

A) 10

B) 13

C) 14

D) 15

Answer: Option B


Let the required number of days be X.

Less person, more days (indirect proportion)

More working hours per day, Less days (indirect proportion)

Persons 30: 39
Working hours/days 6:5

Therefore, 30*6*x = 39*5*12

X = (39*5*12)

X= 13.

Question 3)

If a quarter kg of potato costs 60 paise, how many paise will 200gm cost?

A) 48 paise

B) 54 paise

C) 56 paise

D) 72 paise

Answer: option A

Solution: Let the required weight be x kg

Less weight, less cost (direct Proportion)

Therefore, 250:200::60:x = 250 x x = (200*60)

X = (200*60)/250

X = 48

Question 4)

In a dairy farm, 40 cows eat 40 bags of husk in 40 days. In how many days one cow will eat on a bag of husk?

A) 1

B) 1/10

C) 40

D) 80

Answer: Option C


Let the required number of days be x.

Less cows, more days (Indirect Proportion)

Less bags, Less days (Direct Proportion)

Cow 1:40
Bags 40:1

1*40*x =40*1*40

= x=40.

Question 5)

A flagstaff 17.5 m high casts a shadow of length 40.25 m. The height of the building, which casts a shadow of length 28.75 m under similar conditions, will be:

A) 10.0 m

B) 12.5 m

C) 17.5 m

D) 21.25 m

Answer: option B


Let the height of the building x metres.

Less lengthy shadow, Less in the height (Direct Proportion)

40.25: 28.75: 17.5: X

40.25 * X = 28.75 * 17.5

X = 28.75*17.5/ 40.25

X = 12.5

Attempt CAT Mock Test Now

Read Complete Module on Quantitative Ability

Stay informed, Stay ahead and stay inspired with MBA Rendezvous  

Crucial Dates, You Should not Miss

TAPMI, Manipal
Admission Application closes on January 16, 2018 for 2018-20
BIMTECH, Greater Noida
Admissions open for PGDM Programmes at BIMTECH. Apply Now !
Lal Bahadur Shastri Institute of Management
Admissions are Open at LBSIM, Delhi. Apply Now !
FORE School of Management
Apply for PGDM & PGDM-IB Programmes. Application Deadline is December 22, 2017.
Goa Institute of Management
PGDM Admissions Open at GIM. Apply Before January 5, 2018
Last Date to Apply for MBA (Full Time) Programme at NIRMA is January 09, 2018
XAT 2018
Application Last Date 30th November 2017
IMI New Delhi
Application closes 4th December 2017
XIM Bhubaneshwar
Last Date 8th December 2017
SIBM Bengaluru
Apply for SNAP 2017 to be held on Dec 17 and apply for SIBM-Bengaluru through the SNAP Form
Institute of Rural Management Anand
IRMASAT will be conducted on February 4,2018, Apply Before December 31,2017
IBSAT 2017
Last date for IBSAT registration is December 12 , 2017
Last date to register for SNAP is 24th November, 2017. Last date for SSBF is 2nd January 2018
SIBM Hyderabad
Apply for SNAP 2017 to be held on Dec 17 and apply for SIBM-Hyderabad through the SNAP Form
K J Somaiya Institute of Management Studies & Research, Mumbai
Last date for Application is 31st Jan, 2018
Application for PGDM 2018-20 at SDMIMD is open till February 28, 2018
Institute of Management Technology
Application closes on November 24, 2017
MDI Murshidabad
Application for PGPM 2018-20 at MDI Murshidabad is open till November 24, 2017

Admission Open Now

Following Colleges are accepting applications.


Admissions open for 2018-20

PGDM, PGDM (HRM), PGDM(B & FS), Executive PGDM

Apply Online