Clearly the difference between Rs. 578.40 and Rs.614.55 is the interest on Rs. 578.40 for 1 year.

Correct Option: B

Clearly the difference between Rs. 578.40 and Rs.614.55 is the interest on Rs. 578.40 for 1 year.
∴ Interest on Rs. 578.40 for 1 year = Rs. 614.55 - Rs. 578.40 = Rs. 36.15
∴ Interest on Rs.100 for 1 year = Rs. (36.15 x 100)/578.40
= Rs. 3615/57840 x 100/1
= Rs. 6.25
= Rs. 6¹/₄

∴ The required rate is .6¹/₄ percent.

Let the sum be Rs. 100 then,
S.I.= Rs.(100 x 5 x 2)/100 =Rs.10
C.l.= Rs.[100 x (1 +5/100)²] =Rs.41/4

∴ difference between C.I. and S.I. = Rs. (41/4-10) = Re.0.25

Correct Option: A

Let the sum be Rs. 100 then,
S.I.= Rs.(100 x 5 x 2)/100 =Rs.10
C.l.= Rs.[100 x (1 +5/100)²] =Rs.41/4

∴ difference between C.I. and S.I. = Rs. (41/4-10) = Re.0.25

⇒ 0.25 : 1.50 : : 100 : P
∴ P = (1.50 x 100) / 0.25 = Rs. 600

∵ P (1 - 10/100)³ = 729
∴ P = Rs.(729 x 10 x 10 x 10)/(9 x 9 x 9)

Correct Option: C

∵ P (1 - 10/100)³ = 729
∴ P = Rs.(729 x 10 x 10 x 10)/(9 x 9 x 9) = Rs. 1000

Increase% = (1/8) x 100% = 12.5%
Height after 2 years =64 x {1 +25/(2 x 100)}²

Correct Option: D

Increase% = (1/8) x 100% = 12.5%
Height after 2 years =64 x {1 +25/(2 x 100)}²
= 64 x 9/8 x 9/8
= 81 cm

Principal = (P.W. of Rs. 121 due 1 year later) + (P.W. of Rs. 121 due 2 years later)
= Rs. [ 121 /(1 + 10/100) + (121 / (1 + 10/100)²]

Correct Option: B

Principal = (P.W. of Rs. 121 due 1 year later) + (P.W. of Rs. 121 due 2 years later)
= Rs. [ 121 /(1 + 10/100) + (121 / (1 + 10/100)²]
= Rs. 210