Percenatge Problem

IMO 30 kgs of alloy must be added.

Hai Sudhir.....I want explained answers of the above questions.....I dont know how to proceed the above problems.......can u help me?

assumme that total after increased lead will be 50+X

Tin would remain the same.

lead would be 30+x ( 60% 0f 50)

equation 50+x = 20+ (50+x)*75%

solve this to get X = 30.

is the 2nd question correct...???

Answer is 1 for 2nd question..

average of 3 students us 48 = 144 . one subject he scored 64 hence two subjects he scored 144-64 =80 ( minimum is 35 hence he wud have cleared those 2 subjects)

total he scored 40% which is 7*100*40% = 280

hence the average of 4 subjects = 280- 144 ( avg of 3 subjects)
= 136
minimum he shud get 35 in each subject to pass.. hence 35*4 = 140

therefore the minimum no the subjects he would have failed is 1 .

let us know the OA.

ya.....2nd question is right...

Thanks Sudhir...