Directions (1-5): What will come in place in ? in the following questions?

1. 38% of 4500 – 25% of ? = 1640
   A) 240
   B) 265
   C) 280
   D) 320
   E) None of these
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option C
   
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2. (0.64)⁴ ÷ (0.512)³ × (0.8)⁴ = (0.8)^{? + 3}
   A) 2
   B) 1
   C) 0
   D) 4
   E) None of these
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option C
   
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3. 3648.24 + 364.824 ÷ ? – 36.4824 = 3794.1696
   A) 2
   B) 6
   C) 4
   D) 5
   E) 8
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option A
   
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4. 42% of ? = 3147 + 4258 – 7212 ÷ 12
   A) 16200
   B) 15400
   C) 18600
   D) 12800
   E) 14400
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option A
   
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5. 16121.50 – 48.25 + 3423.75 – 12016 + 512 ÷ 8 = ?
   A) 7545
   B) 7555
   C) 7575
   D) 7495
   E) 7515
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option A
   
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6. A box contains 6 black and 14 white balls, out of which 3 black and 5 white balls are defective. If we choose two balls at random, what is the probability that either both are white or both are non-defective?
   A) 141/190
   B) 123/190
   C) 121/190
   D) 123/199
   E) None of these
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option C
   Solution –
   Required probability- ¹⁴C₂/²⁰C₂ + ¹²C₂/²⁰C2₂ – ⁹C₂/²⁰C₂ = 121/190 [/su_spoiler]
7. In a class, the average age of some boys is 16 years, and average age of 16 teachers is 56 years. If the average age of the combined group of all the teachers and boys is 20, then the number of students is
   A) 156
   B) 144
   C) 136
   D) 88
   E) 168
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option B
   Solution –
   Use allegation method
   number of boys ‘x’           :             number of teacher’16’
   .      16                                                      56
   .                                      20 
   .    (56-20)=36                                  (20-16)=4
   .     So 36/4 = 9/1
   Now, x/16= 9/1, x=144
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8. If the CI on a certain sum for 2 yrs at 10% per annum is Rs. 3150, what would be the SI on same rate for same time?
   A) 2500
   B) 3000
   C) 2800
   D) 2200
   E) None of these
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option B
   Solution –
   Let principal = Rs x
   CI for 2years in % = 21% (using successive method)
   21% of x = 3150
   x = 15000
   S.I = 15000*2*10/100 = Rs.3000
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9. A started a business with initial investment of rs.12000, after 3 month B invest rs.15000 in this business. After 8 month from starting A withdrew one-fourth of his investment and B further invest 1/15 part of his investment. If at the end of one year the difference between the shares of profit of both is 700, what is the B’s profit share?
   A) 14550
   B) 13550
   C) 13900
   D) 42000
   E) 41250
   [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option C
   Solution –
   (12000*8 + 9000*4) : (15000*5 + 16000*4)
   132 : 139
   Difference in profit sharing ration is= 139x – 132x = 7x
   Given 7x = 700, So x = 100
   B’s profit share = 139x = 13900 [/su_spoiler]
10. There are three taps A, B, and C. A takes thrice as much time as B and C together to fill the tank. B takes twice as much time as A and C to fill the tank. In how much time can the Tap C fill the tank individually, if they would require 10 hours to fill the tank, when opened simultaneously?
    A) 16 hours
    B) 12 hours
    C) 22 hours
    D) 20 hours
    E) 24 hours
    [su_spoiler title=” View Answer ” icon=”chevron-circle”] Option E
    Solution –
    Let A, B, C fills a, b, c units per hour.
    Total units = 10*(a+b+C)
    Now, 3a = b+c and 2b = a+c
    Solving both,
    b = 4c/5 and a = 3c/5
    total units of work = 10c*(4/5 + 3/5 + 1) = 24c
    done by C in 24c/c = 24 hours [/su_spoiler]