Question

27.1: b: h=.2..5: 7. If lbh =51030 m, then. LSA of a cuboid is
1) 7948 m?
2) 7838 m 3) 7938 m?
4) 9558​

Answer 1

Answer:

$2x \times 5x \times 7x = 51030 \\ 10x {}^{2} \times 7x = 51030 \\ 70x {}^{3} = 51030 \\ x {}^{3} = 51030 \div 70 \\ x {}^{3} = 729 \\ x = 9 \\ l = 2x \: = 2 \times 9 = 18 \\ b = 5x = 5 \times 9 = 45 \\ h = 7x = 7 \times 9 = 63 \\ lsa = 2(l + b)h \\ \: \: \: \: \: \: = 2(18 + 45)(63) \\ \: \: \: \: \: \: = 2(63)(63) \\ \: \: \: \: \: \: = 2(3969) \\ \: \: \: \: \: \: = 7938$

so the answer is 7938m

Answer 2

Answer:

l:b:h=2:5:7=2x:5x:7x

here,

$lbh = 51030 \\ > 2x \times 5x \times 7x = 51030 \\ > 70x3 = 51030 \\ > x3= 729$

so,

X=9

so,

$l = 2x = 2 \times 9 = 18 \\ b = 5x = 5 \times 9 = 45 \\ h = 7x = 7 \times 9 = 63$

now,

lsa = 2h(l + b) =2×63(18+45)=126×63=7938