__Aptitude Shortcuts Method for Average Related Problems Type-I__
Aptitude Shortcuts methods that used in aptitude questions related
to Average Problems were given below in pdf. Candidates those who are preparing
for SSC/FCI and all other competitive exams can use this.

**Model Question:**

1.) The Average
Cost of 8 pens and 5 pencils is Rs. 25, and the average cost of 4 pens

and 7 pencils
is Rs. 21. What is the total cost of 18 pens and 18 pencils?

**Given:**

Average Cost of 8 pens and 5 pencils= Rs. 25

Average Cost of 4 pens and 7 pencils= Rs. 21

Asked: the total cost of 18 pens and 18 pencils=?

**Shortcut Method:**

Initially we
have to find the total cost of 8 pens and 5 pencils,

8 pens + 5
pencils = 25 × 13

**Note:**To find the total cost of the 8 pens and 5 pencils we are multiplying the average

cost and number
of the pens and pencils.

So, 8 pens + 5
pencils= 325 --à
equation (1)

Likewise we are
calculating the total cost of 4 pens and 7 pencils,

4 pens + 7
pencils = 21 × 11

4 pens + 7
pencils = 231à
equation (2)

Now we have to
add Equation (1) and (2)

12 pens + 12
pencils = 325 + 231

12 pens + 12
pencils = 556

Here we got the
total cost of 12 pen and 12 pencils, and in the problem they asked the

total cost of
18 pens and 18 pencils.

For that we are
using a simple matrix method;

12 ⋯ 556

⋮ ⋱ ⋮

18 ⋯ 𝑥

**Explanation for the above matrix method:**

- In the above matrix methods in four data one data should be unknown then only we can apply this method.
- Here we take that, total cost of 12 pens and pencils is 556, and then what is the total cost of 18 pens and pencils.
- Take ‘x’ as the total cost of 18 pens and 18 pencils Cross multiply the above matrix equation then we will get as,

12x= 10008

x=10008/12

x= 834

**Answer= 834; the total cost of 18 pens and 18 pencils are Rs. 834**

**People also Visited:**

**Aptitude Shortcut Methods and Rules for Profit and Loss Download in PDF****Aptitude Shortcut Methods and Rules for Square root and Cube root Download in PDF****Aptitude Shortcut Methods and Rules for Fraction Download in PDF****Aptitude Shortcut Methods and Rules for Percentage Download in PDF**__Aptitude Shortcut Methods and Rules for Time and Work Problems__