10. By what per cent above the cost price should a dealer mark a pen so that after allowing a
discount of 4% he gains 20%?
Answers
Method 1--
let mark price is 100
4% discount means selling price = 96
while selling on 96, 20% gain.
20% = 1/5 ; means if 5 is cost price , then (5+1) =6 would be selling price ( because 20% profit means 1₹ profit on 5₹ cost price)
so, 6 unit = 96
1 unit = 16 then cost price 5 unit = 16×5 = 80₹
now, cost price 80₹; marked price 100₹ then percentage = {(100-80)/80}×100 = 100/4 = 25%
Method 2---
use formula
total effect = x + y + (xy/100)
here total gain = 20 , x = ? , y = (-4) discount
20 = x -4 - (4x/100)
20 = 0.96x - 4
24 = 0.96x or x = 24/0.96 = 25
so 25%
Step-by-step explanation:
Given sin(A+B)=1
⇒sin(A+B)=sin90
o
(∵sin90
o
=1)
⇒A+B=90
o
…………(1)
Again, cos(A−B)=
3
/2
⇒cos(A−B)=cos30
o
(∵cos30
o
=
3
/2)
⇒A−B=30
o
…………(2)
Adding (1)+(2)
A+B+A−B=90
o
+30
o
⇒2A=120
o
⇒A=120/2
⇒A=60
o
Putting A=60
o
in equation-(2) we get
A−B=30
o
⇒60
o
−B=30
o
⇒60
o
−30
o
=B
⇒B=30
o
∴A=60
o
;B=30
o
.