20 packs contain 4 B’s The probability that 1 pack will have a B is 420 or 15.

log_a (0.0196) = 2

0.0196 = a₂

19610000⁄ = a₂

√19610000⁄ = a

a = 14100 = 0.14

140 part cool by first AC in 1 minute

145 part cool by second AC in 1 minute

17360 = 140 + 145 = part cool by both AC in 1 minute.

Total time = 36017 = 21.2 ≈ About 22 minutes

Let Principal be Rs. X

Amount = Rs. 10x

S.I. = (A - P) Rs. 9x

S. I. = P∗R∗T100⁄

9x = x∗R∗20100⁄

R = 45%

0.5 kg flour can make 5 cup cakes i.e. one cup cake can be made using 100 gm of flour. 4.2 kg or 4200 gm flour can make (4200100?) = 42 cup cakes.