A 1kg rock dropped into ocean would take 37 minutes to reach 6660m.if the rocks dropped steadily, how for would it fall in 1minute
Answers
Answer:
» Four numbers are in AP whose sum is 40.
• Let four numbers be (a - 3d), (a - d), (a + d), (a + 3d)
A.T.Q.
=> a - 3d + a - d + a + d + a + 3d = 40
=> 4a = 40
=> a = 40/4
=> a = 10 _______ (eq 1)
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» The ratio of the product of first and fourth term is 2:3.
\dfrac{a \: - \: 3d}{a \: + \: 3d} \: = \: \dfrac{2}{3}
a+3d
a−3d
=
3
2
Cross-multiply them..
=> 3(a - 3d) = 2(a + 3d)
=> 3a - 9d = 2a + 6d
=> 3(10) - 9d = 2(10) + 6d [From (eq 1)]
=> 30 - 9d = 20 + 6d
=> 30 - 20 = 6d + 9d
=> 10 = 15d
=> d = 10/15
=> d = 2/3 ________ (eq 2)
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» We have to find the numbers. (Means AP.)
• a - 3d = 10 - 3(2/3)
=> 10 - 2 = 8
• a - d = 10 - 2/3
=> (30 - 2)/3 = 28/3
• a + d = 10 + 2/3
=> (30 + 2)/3 = 32/3
• a + 3d = 10 + 3(2/3)
=> 10 + 2 = 12
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\textbf{Number are : 8, 28/3, 32/3 and 12}Number are : 8, 28/3, 32/3 and 12
__________ [ANSWER]
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✡ From above calculations we get numbers 8, 28/3, 32/3 and 12
Add all the numbers.
=> 8 + 28/3 + 32/3 + 12
=> (24 + 28 + 32 + 28)3
=> 120/3
=> 40
_______ [HENCE VERIFIED]
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