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If sin x + cot x = a and cosec x + tan x = b, find the value of cos x.
Sin x + cot x = a
1/sin x + 1/cot x = b
(Cot x + sin x)/(sin x cot x) = b
a/ (sin x cot x) = b
a/b = sin x cot x
a/b = sin x cos x/sinx
a/b = cos x
A company produces 26678 toys in each of the first two months of a year. Due to man power shortage the number of toys produced reduces in the third month so that the average production in the three months falls to 25490. Find the reduction the production of toys in the third month with respect to the second month.
Average production in 3 months = 25490
Total production in 3 months = 25490×3 = 76470
Production in first two months = 26678 + 26678 = 53356
Production in third month = 76470 – 53356 = 23114
Reduction in production = 26678 – 23114 = 3564
The cost of 10 vegetables is equal to the cost of 15 fruits. The cost of 9 fruits is equal to that of 10 sweets. The cost of 5 sweets is equal to the cost of 6 chocolates. If the cost of 10 vegetables is 300, find the cost of 10 fruits, 5 sweets and 5 chocolates.
Let V, F, S, C represent cost of vegetable, fruit, sweet, chocolate respectively.
10V = 15F
So, 30V = 45F
9F = 10S
So, 45F = 50S
5S = 6C
So, 50S = 60C
30V = 45F = 50S = 60C
Ratio of cost of V : F : S : C = 1/30 : 1/45 : 1/50 : 1/60
= 30 : 20 : 18 : 15
Cost of 10V = 300
Cost of 1 V = 30
Cost of 1 F = 20
Cost of 1 S = 18
Cost of 1 C = 15
Cost of (10F + 5S + 5C) = 10×20 + 5×18 + 5×15
=200 + 90 + 75
= 365
The mean of 25 values is found out to be 40. Upon observation it is found that a value has been written as 25 instead of 50. Find the original mean.
Mean=40
Number of observation = 25
Total = 40×25 = 1000
50 has been wrongly entered as 25
So, sum of observation=1000 – 25 + 50 = 1025
Mean = 1025/25 = 41
A man sells an item for Rs. 2400 at 10% discount. For how much does he need to sell 2 items to gain 5 %?
Let CP for man be x
SP = 0.9x = 2400
x = 8000/3
For 5% profit, SP = 1.05 × 8000/3
= 2800
SP of 2 items = 2800 × 2 = 5600
A man buys an item at Rs. 42000. If he promises to pay the amount at 8% Simple interest in 12 equal monthly installments, what is the amount that he pays every month as installment?
SI for 12 months = SI for 1 year = 42000×8/100
= 3360
Amount = 42000 + 3360 = 45360
Monthly installment = 45360/12 = 3780
A man sells basmati rice of first quality at which costs Rs. 250/kg with inferior variety that costs Rs. 120/kg. If he sells 10 kg of the mixture at Rs. 2235.2 and earns 10% profit, find the ratio of first quality rice to that of inferior quality rice.
Let there be x kg of first quality rice and 10 – x kg of inferior rice
Cost of 10kg = 250x + 120(10 – x)
= 130x + 1200
SP of 10 kg = 2235.2
This gives 10% profit. Let CP = y
1.1y = 2235.2
Y = 2032
But, this is equal to 130x + 1200
130x + 1200 = 2032
130x = 832
x = 6.4kg (First quality rice)
Inferior quality rice = 3.6 kg
Ratio = 6.4/3.6 = 64/36 = 16 : 9
27 men can do a piece of work in 4 days less than that of the number of days which 9 men take to do the work. Find the time taken by 6 men to do the work.
M1T1/W1 = M2T2/W2
Let the Time taken by 9 men = x days
Time taken by 27 men to complete the work be x - 4 days
27×(x – 4)/1 = 9x
27x – 108 = 9x
18x = 108
x = 6 days
Similarly, 9×6/1 = 6×y/1(y is time taken by 6 people to do the work)
y = 9 days
Find the last digit of the following expression.
276×83×2323×1151
Cyclicity of 7 is 4
So, last digit of 276 is 9
Last digit of 83 = 2
Cyclicity of 3 = 4
So, last digit of 2323 = 7
Last digit of expression = Last digit of 9×2×7 = 6
The ratio of ages of A and B before ten years was 4 : 9. If the sum of their ages now is 72, find the ratio of their ages after 4 years.
Let their ages be x and y
x + y = 72
Before 10 years, (x – 10)/(y – 10) = 4/9
9x – 90 = 4y – 40
9x – 4y = 50
4x + 4y = 288
Adding these two equations, 13x = 338
x = 26
So, y = 36
After 4 years, ages are 30, 50
Ratio = 3 : 5
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