missing option on online test geometric sequences

[rdm750]

The solution mentions an extra choice f but it is not visible (tried ie and chrome same issue) at all.

I looked into the view source code (pasted as well) and it seems to be missing there as well...

It came up on the test5 (q18/20) sec2 math.
seems like i marked the correct answer choices except f...
thanks!
Rohit

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<input type="checkbox" name="radAnswer" value="5" />


<div class="label " for="square_checkbox" value="5">

<span style="float:right;display:none;padding-right:60px;" class="rightwrongdiv">
<img src="../../cat/images/delete.gif" alt="" name="img5" id="img5" width="13" height="13" hspace="0" border="0" align="bottom">
</span>
<p><em>a, </em>2<em>b, </em>4<em>c, </em>8<em>d, </em>16<em>e, </em>32<em>f</em></p>





</div>




</div>

</div>

<div style="clear:both;margin-top:10px;">&nbsp;</div>
<div style="float:left;"><input class="btn" type="button" id="btnshowexpl" name="showexpl" value="Show explanation"></div>
<div style="float:left;"><input type="button" class="btn" id="btnhideexpl" name="hideexpl" value="Hide explanation"></div>
<div style="clear:both;margin-bottom:10px;"></div>
<div class="" id="div_explain" style="display:none; text-align:left;"><div style="margin: 0in 0in 10pt">To get a handle on this tough sequence problem, it would be best to try an example by picking numbers. We can try to think of a basic example, where we begin with the number 2. We can then use 2 as our constant multiplier, so each subsequent term would be as follows:</div>
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a, b, c, d, e, f

A geometric sequence is a sequence in which each term after the first is equal to the product of the preceding term and a constant. If the list of numbers shown above is a geometric sequence, then which of the following must also be a geometric sequence?
Indicate all that apply.



3a, 3b, 3c, 3d, 3e, 3f

a + 2, b + 2, c + 2, d + 2, e + 2, f + 2

a2, b2, c2, d2, e2, f2

a + b, b+ c, c + d, d + e, e+ f


a, 2b, 4c, 8d, 16e, 32f









To get a handle on this tough sequence problem, it would be best to try an example by picking numbers. We can try to think of a basic example, where we begin with the number 2. We can then use 2 as our constant multiplier, so each subsequent term would be as follows:

2, 4, 8, 16, 32, 64…

Now we can use this test set to check the possible choices.

A. 3(2), 3(4), 3(8), 3(16), 3(32), 3(64) = 6, 12, 24, 48…
Notice that each term is still increasing by a constant multiple, 2. This is still a geometric sequence.

B. 2+2, 4+2, 8+2, 16+2, 32+2, 64+2 = 4, 6, 10, 18, 34, 66
We can start by testing the first few terms in the sequence. To move from 4 to 6, we must multiply by 3/2, but to move from 6 to 10, we multiply by 5/3. Because these multipliers are not the same, this cannot be a geometric sequence.

C. 22, 42, 82, 162, 322, 642 = 4, 16, 64, 256, 1024, 4096
To move from 4 to 16, we multiply by 4. To move from 16 to 64, we also multiply by 4. Because the multiplier is the same through the entire sequence, this is still a geometric sequence.

D. 2+4, 4+8, 8+16, 16+32, 32+64 = 6, 12, 24, 48, 96
Notice that each term is exactly 2 times the term before it. This is still a geometric sequence.

E. 2, 2(4), 4(8), 8(16), 16(32), 32(64) = 2, 8, 32, 128, 512, 2048
Each term is increasing by a multiply of 4, so this is still a geometric sequence.

F.
This tough sequence is still increasing by a constant multiple,, so this is a geometric sequence.
The correct answers are A, C, D, E, and F.

[esledge]

Hi Rohit,

Thanks for bringing this to our attention. Choice F required images, not just text; these weren't entered properly initially. The issue has been fixed.

Thanks again,
Emily Sledge

[rdm750]

I am able to see the last sequence.
thanks!
Rohit Malgaonkar

[tommywallach]

No problem, Rohit! We always love to correct our errors!

-t